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PMID:23922206

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Citation

Zhong, L, Zhou, W, Wang, H, Ding, S, Lu, Q, Wen, X, Peng, L, Zhang, L and Lu, C (2013) Chloroplast small heat shock protein HSP21 interacts with plastid nucleoid protein pTAC5 and is essential for chloroplast development in Arabidopsis under heat stress. Plant Cell 25:2925-43

Abstract

Compared with small heat shock proteins (sHSPs) in other organisms, those in plants are the most abundant and diverse. However, the molecular mechanisms by which sHSPs are involved in cell protection remain unknown. Here, we characterized the role of HSP21, a plastid nucleoid-localized sHSP, in chloroplast development under heat stress. We show that an Arabidopsis thaliana knockout mutant of HSP21 had an ivory phenotype under heat stress. Quantitative real-time RT-PCR, run-on transcription, RNA gel blot, and polysome association analyses demonstrated that HSP21 is involved in plastid-encoded RNA polymerase (PEP)-dependent transcription. We found that the plastid nucleoid protein pTAC5 was an HSP21 target. pTAC5 has a C4-type zinc finger similar to that of Escherichia coli DnaJ and zinc-dependent disulfide isomerase activity. Reduction of pTAC5 expression by RNA interference led to similar phenotypic effects as observed in hsp21. HSP21 and pTAC5 formed a complex that was associated mainly with the PEP complex. HSP21 and pTAC5 were associated with the PEP complex not only during transcription initiation, but also during elongation and termination. Our results suggest that HSP21 and pTAC5 are required for chloroplast development under heat stress by maintaining PEP function.

Links

PubMed PMC3784589 Online version:10.1105/tpc.113.111229

Keywords


Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ARATH:PTAC5

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:P31170

F

Seeded From UniProt

complete

ARATH:PTAC5

involved_in

GO:0006355: regulation of transcription, DNA-templated

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:PTAC5

involved_in

GO:0009658: chloroplast organization

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:PTAC5

located_in

GO:0042644: chloroplast nucleoid

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:PTAC5

involved_in

GO:0009416: response to light stimulus

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:PTAC5

involved_in

GO:0009408: response to heat

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:PTAC5

colocalizes_with

GO:0000427: plastid-encoded plastid RNA polymerase complex

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:PTAC5

involved_in

GO:0042793: plastid transcription

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:HS25P

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:A1A6M1

F

Seeded From UniProt

complete

ARATH:HS25P

involved_in

GO:0006355: regulation of transcription, DNA-templated

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:HS25P

involved_in

GO:0009658: chloroplast organization

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:HS25P

located_in

GO:0042644: chloroplast nucleoid

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:HS25P

involved_in

GO:0009416: response to light stimulus

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:HS25P

involved_in

GO:0009408: response to heat

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:HS25P

involved_in

GO:0009408: response to heat

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:HS25P

colocalizes_with

GO:0000427: plastid-encoded plastid RNA polymerase complex

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:A1A6M1

GO:0003756: protein disulfide isomerase activity

ECO:0000314:

F

Figure 10B. Denatured RNase A was refolded into its active form in the presence of pTAC5. The activity of the RNase A was tested at intervals throughout the assay. The percent of active RNase A increased after exposure to pTAC5. After 300 minutes, the RNase A activity was 30% higher than it was at the beginning of the assay.

complete
CACAO 9749

ARATH:A1A6M1

enables

GO:0003756: protein disulfide isomerase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:A1A6M1

part_of

GO:0042644: chloroplast nucleoid

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:A1A6M1

involved_in

GO:0009408: response to heat

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:A1A6M1

involved_in

GO:0009658: chloroplast organization

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:A1A6M1

colocalizes_with

GO:0000427: plastid-encoded plastid RNA polymerase complex

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

ARATH:A1A6M1

involved_in

GO:0006355: regulation of transcription, DNA-templated

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:A1A6M1

involved_in

GO:0042793: plastid transcription

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:A1A6M1

involved_in

GO:0009416: response to light stimulus

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

See also

References

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