Báo cáo khoa học: Invited speakers pot

Invited speakers

I01

Please view Plenary lectures

I02

Abstract missing, please view Abstract Addendum

I03

Aquaporin water channels in health and

disease

M. Amiry-Moghaddam

University of Oslo, Oslo, Norway

The water permeability of biological membranes has been a long￾standing problem in physiology, but the proteins responsible for

this remained unknown until discovery of the aquaporin 1

(AQP1) water channel protein. Peter Agre received Nobel prize in

Chemistry in 2003 for this discovery. AQP1 is selectively perme￾ated by water driven by osmotic gradients. The atomic structure

of human AQP1 has been defined. Each subunit of the tetramer

contains an individual aqueous pore that permits single-file

passage of water molecules but interrupts the hydrogen bonding

needed for passage of protons. At least 12 mammalian aquaporins

have been identified, and these are selectively permeated by water

(aquaporins) or water plus glycerol (aquaglyceroporins) and more

than 200 members of the aquaporin family have been found in

plants, microbials, invertebrates and vertebrates. Research in the

past decade has shown that aquaporins are not only involved in

important physiological processes such as maintenance of body

water homeostasis, but are also involved in pathological condi￾tions such as nephrogenic diabetes insipidus, cataract, metabolic

syndrome, brain edema and epilepsy.

I04

Abstract missing, please view Abstract Addendum

I05

Electron transfer routes in photosynthetic

membranes – impact on biohydrogen

production

E-M. Aro, P. Zhang, M. Eisenhut, Y. Allahverdiyeva

and N. Battchikova

University of Turku, Turku, Finland

Optimization of electron transfer from water to biohydrogen pro￾duction in a model organism Synechocystis sp. PCC 6083

involves several steps. PSII function can be improved by intro￾ducing a proper PSII reaction center D1 protein (encoded by the

psbA gene family). To this end, an expression of a specific psbA

gene that encodes a D1’ protein was detected under anaerobic

conditions. We have also demonstrated a novel and crucial func￾tion for Flavodiiron (FDP) proteins Flv2 and Flv4 in photopro￾tection of PSII. The rate of accumulation of flv2 and flv4

transcripts upon shift of cells from high to low CO2 is strongly

dependent on light intensity. Characterization of FDP inactiva￾tion mutants revealed a specific decline in PSII centers and

impaired translation of the D1 protein in Dflv2 and Dflv4 when

grown at air level CO2 whereas at high CO2 the FPDs were dis￾pensable. Dflv2 and Dflv4 were also more susceptible to high light

induced inhibition of PSII than WT or Dflv1 and Dflv3. Of the

four flavodiiron proteins (Flv1-4) in Synechocystis 6803, a physi￾ological function of Flv1 and Flv3 is in the Mehler reaction. Up

to 30% of electrons derived from water by PSII may be directed

to molecular oxygen via Flv1 and Flv3, and thus this route might

seriously compete for electrons with the hydrogenase. Besides

FDPs, the multiple NDH-1 complexes in cyanobacterial thyla￾koid membranes have a crucial role in electron transfer reactions,

particularly in cyclic electron transfer around PSI, in respiratory

electron transfer and in carbon concentrating mechanisms. More￾over, interplay between the FDPs and NDH-1 complexes is dem￾onstrated to occur in electron transfer reactions.

I06

Global transcriptional regulation of the gut

microbiota and its impact on host physiology

F. Ba¨ckhed

University of Gothenburg, Gothenburg, Sweden

The adult intestine contains around 100 trillion bacteria, a num￾ber 10 times greater than the number of human cells in our body.

This complex ecosystem (gut microbiota) has complemented our

own genome with several functions that affects human health:

modulation of metabolism, development of the immune system,

and protection against enteric infections. Recent data have impli￾cated the gut microbiota to be involved in obesity, which is asso￾ciated with an altered gut microbiota. The gut microbiota can

affect host metabolism either directly or indirectly by affecting

gene expression. Germ-free mice have provided an important tool

to investigate the underlying molecular mechanisms for how the

gut microbiota affects host physiology. By using metabolomics

and lipidomics we have recently found that the gut microbiota

directly affects the serum metabolome and serum, liver, and adi￾pose lipidomes. By comparing the transcriptional profile along

the length of the gut in germ-free and conventionally raised mice

we have demonstrated altered expression of several hormones

that are produced by the epithelium. Additional experiments

revealed that microbial regulation of gene expression in the small

intestine could directly affect host metabolism.

Furthermore, we could demonstrate a rapid induction of genes

involved in the innate immune system in the epithelium as well

as recruitment of immune cells to the mucosa. Taken together

the gut microbiota should be considered as an organ by itself

that has major effects on host metabolism and physiology, were

perturbations may cause or promote disease.

I07

Folding and redox processes in the

mitochondria

L. Banci

CERM & Department of Chemistry, University of Florence, Sesto

Fiorentino (Florence), Italy

A number of proteins undergo their folding through various

states that are dependent on the cellular compartment and on

compartment-specific protein components. A number of nuclear￾encoded proteins, lacking the mitochondrial target sequence,

enter mitochondria through transmembrane channels and get

trapped in the IMS through oxidative folding processes. These

proteins are characterized by disulfide bonds whose formation is

combined to protein folding. Disulfide bond formation is kineti￾Invited speakers Abstracts

FEBS Journal 277 (Suppl. 1) 5–36 (2010) ª 2010 The Authors Journal compilation ª 2010 Federation of European Biochemical Societies 5

cally slow and is catalyzed by a protein, Mia40, which is part of

a disulfide relay system. In this system the electron flow goes

from Mia40 substrates up to cytochrome c and cytochrome c oxi￾dase. Significantly some of the Mia40 substrates are proteins

responsible for incorporating copper in cytochrome c oxidase.

This behaviour shows how various processes occurring in the

same cellular compartment are tightly connected and interlinked,

and therefore only a charactrization at ‘system’ level can fully

describe functional processes. A few examples of folding pro￾cesses will be presented and discussed.

I08

New insights into hepatitis C virus replication

and persistence

R. Bartenschlager

Department of Infectious Diseases, Molecular Virology, University

of Heidelberg, Heidelberg, Germany

Hepatitis C viruses (HCV) comprise the sole genus hepacivirus in

the family Flaviviridae. These viruses have in common a single

strand RNA genome of positive polarity encoding for a single

polyprotein that is cleaved by host and viral proteases. Studies of

the HCV replication cycle have become possible by the develop￾ment of highly efficient and robust cell culture systems. By using

these techniques four molecules (CD81, scavenger receptor class

B type I; claudin-1 and occludin) that are essential for infection

of hepatocytes have been identified and validated. Moreover,

important insights into the biogenesis and architecture of the

membranous replication complex induced upon viral infection

have been gained. Finally, it was found that HCV assembly

occurs in close association with lipid droplets and the host cell

machinery required for the synthesis of very-low-density-lipopro￾tein (VLDL). As a net result of the assembly reaction, infectious

virus particles are formed that are unique in structure and com￾position and that resemble most closely LDL.

A hallmark of HCV infection is the high rate of persistence

(~80%). It was found that the viral serine-type protease NS3 is a

key factor that blocks the induction of antiviral cytokines, esp.

type 1 interferon (IFN) by proteolytic cleavage of adaptor pro￾teins involved in RIG-I and TLR-3 dependent signalling. Apart

from blocking innate immunity, HCV overcomes adaptive

immune responses by multiple strategies including antigenic vari￾ability. Moreover, the tight association of HCV particles with lip￾ids appears to impair virus neutralization. Thus HCV utilizes

multiple strategies to establish persistence.

I09

The billion protein question

A. Bateman

Wellcome Trust Genome Campus, Hinxton, UK

Next generation sequencing is pouring out incredible amounts of

data. We are inevitably moving towards the day when we know

1 billion protein sequences. This is both exciting and terrifying. I

will discuss ways we might deal with the data deluge. Will we all

need to become Bioinformaticians?

I10

Salmonella metabolism during infection

D. Bumann

Biozentrum, University of Basel, Basel, Switzerland

Metabolism is an important aspect of Salmonella biology during

infection. However, individual metabolic perturbations rarely

diminish Salmonella virulence in a mouse typhoid fever model.

To understand underlying causes for this large-scale enzyme dis￾pensability, we used in silico modeling combined with systematic

experimental analysis. Our genome-scale metabolic in silico

model correctly predicts virulence phenotypes of more than 92%

of 849 experimentally characterized Salmonella mutants. Model￾ing and experimental analysis of multiple metabolic mutations

revealed a minor impact of network redundancy on overall

robustness. However, the host microenvironment provides diverse

nutrients that are mainly responsible for extensive Salmonella

robustness against perturbation. Interestingly, genome compari￾sons suggest that many other pathogens might encounter similar

nutritional patterns in their hosts that markedly differ from habi￾tats of environmental microbes.

I11

Designer cellulosomes: Synthetic

multi-enzyme macromolecular complexes

E. Bayer

Department of Biological Chemistry, The Weizmann Institute of

Science, Rehovot, Israel

Cellulosomes are intricate multi-enzyme machines produced by

anaerobic cellulolytic microorganisms, designed for efficient

decomposition of plant cell wall polysaccharides, notably cellu￾lose – the most abundant renewable organic polymer on Earth.

The cellulosome complex consists of interlocking, multi-modular,

structural and enzymatic subunits, which fit together in a Lego￾like arrangement. We have harnessed the molecular logic of the

cellulosome components and have developed methodologies to

re-tool its precise structural organization. For this purpose, func￾tional modular parts of cellulosome subunits from different

microorganisms are mixed and matched by recombinant means

to produce chimaeric products, which can be fitted together in a

controlled manner into novel cellulosome-like structures. The

resultant designer cellulosomes are functional, and their cellulo￾lytic capacities approach and frequently surpass those of equiva￾lent free enzyme systems. Our approach is designed to better

understand these intercomponent interactions, to discover how

the cellulosome is constructed and how cellulosome architecture

contributes to the enhanced synergistic activities of its enzyme

components. Knowledge of these interactions provides a broad

platform for biotechnological and nanotechnological applica￾tions, including prospects for conversion of plant cell wall bio￾mass to biofuels – a crucial goal of global importance in the 21st

century for all mankind.

I12

Pathophysiology of the mitochondrial

permeability transition

P. Bernardi

Biomedical Sciences, University of Padova, Padova, Italy

The mitochondrial permeability transition (PT) is a Ca2+-depen￾dent increase of mitochondrial inner membrane permeability to

solutes with molecular masses up to about 1500 Da [Hunter DR

et al (1976) J Biol Chem 251: 5069–5077]. Its occurrence is always

accompanied by depolarization, while onset of matrix swelling,

depletion of matrix pyridine nucleotides, outer membrane rupture

and release of intermembrane proteins including cytochrome c

depend on the open time. The PT is due to the reversible opening

of a high-conductance, voltage-dependent channel in the inner

mitochondrial membrane, the PT pore (PTP). In spite of many

efforts, its molecular identity remains unknown [reviewed in Ber￾nardi P et al (2006) FEBS J 273: 2077–2099]. In this lecture I

shall cover the essential aspects of PTP pathophysiology, with

specific emphasis on the role of matrix cyclophilin D [Giorgio V

et al (2010) Biochim Biophys Acta doi:10.1016/j.bbabio.2009.12.006];

Abstracts Invited speakers

6 FEBS Journal 277 (Suppl. 1) 5–36 (2010) ª 2010 The Authors Journal compilation ª 2010 Federation of European Biochemical Societies

the mechanism of action of cyclosporin A [Basso E et al (2008) J

Biol Chem 283: 26307–26311]; the modulation by the proton elec￾trochemical gradient [Bernardi P (1992) J Biol Chem 267: 8834–

8839] and redox effectors [Petronilli V et al (1994) J Biol Chem

269: 16638–16642]; and the consequences of PTP opening as a

key to understanding its role in cell dysfunction and death. From

this analysis the PTP emerges as a viable target for therapeutic

intervention in cancer [Rasola A et al (2010) FEBS Lett

doi:10.1016/j.febslet.2010.02.022] and degenerative diseases [Mer￾lini L et al (2008) Proc Natl Acad Sci USA 105: 5225–5229], and

a highly conserved event across species.

I13

Please view Plenary lectures

I14

Relationships between structure and functions

of a major complement inhibitor C4b-binding

protein

A. Blom

Laboratory Medicine Malmo¨, Section of Medical Protein

Chemistry, Lund Universty, Malmo¨, Sweden

The complement system is a vital component of innate immunity

and defends host from infections, alerts adaptive immunity and

clears the organism from unwanted debris such as dying cells,

misfolded proteins and immune complexes. Complement is

tightly regulated by a number of soluble and membrane bound

inhibitors and disturbances of this regulation are related to dis￾eases. C4b-binding protein (C4BP) is a major soluble complement

inhibitor composed of seven identical a-chains and a unique b￾chain, both of which contain complement control protein (CCP)

domains. All subunits are held together at their C-termini via

hydrophobic interactions between amphipathic helices and disul￾phide bridges. We have localized a number of binding sites for

C4BP ligands using recombinant mutants lacking domains, site￾directed mutagenesis, modelling and NMR. The binding site for

C4b, responsible for inhibition of complement, is localized to

CCP1-3 of a-chains and includes mainly positively charged aa.

An overlapping site is used by M proteins of Streptococcus pyog￾enes, an interaction that is one of the immune evasion mecha￾nisms of this pathogen. Overlapping binding sites are also used

by heparin and DNA. The C-terminus of a-chains including

CCP8 binds in turn some components of extracellular matrix and

amyloid. The high affinity (KD 0.2 nM) binding site for antico￾agulant protein S is localized to hydrophobic aa on CCP1 of the

b-chain. The C4BP-PS complex binds avidly to apoptotic cells

allowing their non-inflammatory phagocytosis.

I15

Transgenic plastids as expression factories in

biotechnology

R. Bock

Max-Planck-Institute of Molecular Plant Physiology, Potsdam,

Germany

Genetically modified plants (GM plants) can potentially provide

inexpensive production platforms for pharmaceuticals and nutra￾ceuticals. With the advent of technologies to alter the genetic

information inside plastids (chloroplasts), a new attractive target

for genetic engineering has become available to biotechnologists.

There are considerable attractions of the plastid genome as a

target for the expression of foreign genes. These include (i) the

plastids’ potential for high-level foreign protein expression

(Zhou et al., 2008; Oey et al., 2009), (ii) the possibility of trans￾gene stacking through expression of multiple genes from ope￾rons, and (iii) the absence of position effects and epigenetic gene

silencing mechanisms (Bock, 2007; Bock and Warzecha 2010).

From the biosafety perspective, the major attraction is the exclu￾sively or predominantly maternal inheritance of the plastid gen￾ome in most crop plants, greatly reducing the risk of

uncontrolled pollen spread of transgenes and thus allaying con￾cerns over environmental consequences of GM crop cultivation

(Ruf et al., 2007). Applications of chloroplast engineering in

basic research and biotechnology will depend critically on suc￾cess with extending the crop range of chloroplast transformation

(Ruf et al., 2001) and the feasibility to express transgenes in

non-green plastids (as present in fruits and tubers), which often

are less active in gene expression (Kahlau and Bock, 2008). The

state of the art in engineering the plastid genome of higher

plants will be described and selected applications in two areas of

biotechnology will be discussed: metabolic engineering and

molecular farming.

I16

Structure of chloroplast membrane

organization using cryo-electron tomography

E. Boekema, R. Kouril and G. Oostergetel

University of Groningen, Groningen, Netherlands

The thylakoid membrane architecture of chloroplasts was studied

by cryo-electron tomography (ET) and single particle electron

microscopy (EM). ET reconstructions of isolated, ice-embedded

specimens enabled to resolve the features of photosystem II

(PSII) in the native membrane of granal stacks and to get a close

view of its distribution. 3D analysis of subvolumes containing

PSII complexes provided a 3D structure of the PSII core complex

at 40 A˚ resolution. Comparison with a recently proposed pseudo￾atomic model of the PSII supercomplex (EMBO Journal 28:

3052) revealed the presence of unknown protein densities right

on top of the four peripheral LHCII trimers. The positions of

individual PSII complexes were used to fit an entire membrane

layer with C2S2M2 supercomplexes. Fitting shows that many

supercomplexes must be of smaller size than C2S2M2 super￾complexes, to avoid overlap. The characteristic features of

PSII enabled assignment of the absolute orientation of individual

membranes of granal thylakoid discs and to get a detailed inter￾pretation of the membrane folding pattern. This shows that two

concentrically folded membranes make a unit of four layers. In

that unit, the outer membrane of the grana disc is interrupted on

only one side, whereas the inner membrane is almost closed. It will

be discussed how this is in line or in contrast with curent models.

I17

The genetic landscape of a cell

C. Boone

University of Toronto, Toronto, ON, Canada

A genome-scale genetic interaction map was constructed by

examining 5.4 million gene-gene pairs for synthetic genetic inter￾actions, generating quantitative genetic interaction profiles for

most genes in the budding yeast, Saccharomyces cerevisiae. A

network based on quantitative genetic interaction profiles reveals

a functional map of the cell in which genes of similar biological

processes cluster together in coherent subsets and highly corre￾lated profiles delineate specific pathways to define gene function.

The global network identifies functional cross connections

between all bioprocesses, mapping a cellular wiring diagram of

pleiotropy. Genetic interaction degree correlated with a number

of different gene attributes, which may be informative about

Invited speakers Abstracts

FEBS Journal 277 (Suppl. 1) 5–36 (2010) ª 2010 The Authors Journal compilation ª 2010 Federation of European Biochemical Societies 7