Báo cáo khoa học: Binding affinities and interactions among different heat shock element types and

Binding affinities and interactions among different heat

shock element types and heat shock factors in rice

(Oryza sativa L.)

Dheeraj Mittal1

, Yasuaki Enoki2

, Dhruv Lavania1

, Amanjot Singh1

, Hiroshi Sakurai2 and

Anil Grover1

1 Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India

2 Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Japan

Keywords

heat shock; heat shock element; heat shock

protein; heat shock transcription factor; rice

(Oryza sativa)

Correspondence

A. Grover, Department of Plant Molecular

Biology, University of Delhi South Campus,

New Delhi 110021, India

Fax: +91-11-24115270

Tel: +91-11-24117693/24115097

E-mail: [email protected]

(Received 9 May 2011, revised 27 June

2011, accepted 29 June 2011)

doi:10.1111/j.1742-4658.2011.08229.x

Binding of heat shock factors (Hsfs) to heat shock elements (HSEs) leads to

transcriptional regulation of heat shock genes. Genome-wide, 953 rice genes

contain perfect-type, 695 genes gap-type and 1584 genes step-type HSE

sequences in their 1-kb promoter region. The rice genome contains 13 class

A, eight class B and four class C Hsfs (OsHsfs) and has OsHsf26 (which is

of variant type) genes. Chemical cross-linking analysis of in vitro synthe￾sized OsHsf polypeptides showed formation of homotrimers of OsHsfA2c,

OsHsfA9 and OsHsfB4b proteins. Binding analysis of polypeptides with oli￾gonucleotide probes containing perfect-, gap-, and step-type HSE sequences

showed that OsHsfA2c, OsHsfA9 and OsHsfB4b differentially recognize

various model HSEs as a function of varying reaction temperatures. The

homomeric form of OsHsfA2c and OsHsfB4b proteins was further noted by

the bimolecular fluorescence complementation approach in onion epidermal

cells. In yeast two-hybrid assays, OsHsfB4b showed homomeric interaction

as well as distinct heteromeric interactions with OsHsfA2a, OsHsfA7, OsH￾sfB4c and OsHsf26. Transactivation activity was noted in OsHsfA2c, OsH￾sfA2d, OsHsfA9, OsHsfC1a and OsHsfC1b in yeast cells. These differential

patterns pertaining to binding with HSEs and protein–protein interactions

may have a bearing on the cellular functioning of OsHsfs under a range of

different physiological and environmental conditions.

Structured digital abstract

l HSFA2C binds to HSFA2C by cross-linking study (View interaction)

l HSFA2C physically interacts with HSFA2C by bimolecular fluorescence complementation (View

interaction)

l HSFB4B physically interacts with HSFB4B by bimolecular fluorescence complementation

(View interaction)

l HSFA2A physically interacts with HSFB4B by two hybrid (View interaction)

l HSFB4B binds to HSFB4B by cross-linking study (View interaction)

l HSFB4B physically interacts with HSF26 by two hybrid (View interaction)

l HSFA9 binds to HSFA9 by cross-linking study (View interaction)

l HSFA7 physically interacts with HSFB4B by two hybrid (View interaction)

l HSFB4B physically interacts with HSFB4C by two hybrid (View interaction)

l HSFB4B physically interacts with HSFB4B by two hybrid (View interaction)

Abbreviations

3-AT, 3-amino-1,2,4-triazole; BiFC, bimolecular fluorescence complementation; EGS, ethylglycol bis(succinimidylsuccinate); EMSA,

electrophoretic mobility shift assay; HS, heat shock; HSE, heat shock element; Hsf, heat shock transcription factor; Hsp, heat shock protein.

3076 FEBS Journal 278 (2011) 3076–3085 ª 2011 The Authors Journal compilation ª 2011 FEBS