Dataset Information

Structural analysis and dimerization potential of the human TAF5 subunit of TFIID.

ABSTRACT: TFIID is an essential factor required for RNA polymerase II transcription but remains poorly understood because of its intrinsic complexity. Human TAF5, a 100-kDa subunit of general transcription factor TFIID, is an essential gene and plays a critical role in assembling the 1.2 MDa TFIID complex. We report here a structural analysis of the TAF5 protein. Our structure at 2.2-A resolution of the TAF5-NTD2 domain reveals an alpha-helical domain with distant structural similarity to RNA polymerase II CTD interacting factors. The TAF5-NTD2 domain contains several conserved clefts likely to be critical for TFIID complex assembly. Our biochemical analysis of the human TAF5 protein demonstrates the ability of the N-terminal half of the TAF5 gene to form a flexible, extended dimer, a key property required for the assembly of the TFIID complex.

SUBMITTER: Bhattacharya S

PROVIDER: S-EPMC1783120 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

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Structural analysis and dimerization potential of the human TAF5 subunit of TFIID.

Bhattacharya Suparna S Takada Shinako S Jacobson Raymond H RH

Proceedings of the National Academy of Sciences of the United States of America 20070116 4

TFIID is an essential factor required for RNA polymerase II transcription but remains poorly understood because of its intrinsic complexity. Human TAF5, a 100-kDa subunit of general transcription factor TFIID, is an essential gene and plays a critical role in assembling the 1.2 MDa TFIID complex. We report here a structural analysis of the TAF5 protein. Our structure at 2.2-A resolution of the TAF5-NTD2 domain reveals an alpha-helical domain with distant structural similarity to RNA polymerase I ...[more]

PMID: 17227857

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Project description:When nutrients become scarce, bacteria can enter an extended state of quiescence. A major challenge of this state is how to preserve ribosomes for the return to favorable conditions. Here, we show that the ribosome dimerization protein hibernation-promoting factor (HPF) functions to protect essential ribosomal proteins. Ribosomes isolated from strains lacking HPF (?hpf) or encoding a mutant allele of HPF that binds the ribosome but does not mediate dimerization were substantially depleted of the small subunit proteins S2 and S3. Strikingly, these proteins are located directly at the ribosome dimer interface. We used single-particle cryo-electron microscopy (cryo-EM) to further characterize these ribosomes and observed that a high percentage of ribosomes were missing S2, S3, or both. These data support a model in which the ribosome dimerization activity of HPF evolved to protect labile proteins that are essential for ribosome function. HPF is almost universally conserved in bacteria, and HPF deletions in diverse species exhibit decreased viability during starvation. Our data provide mechanistic insight into this phenotype and establish a mechanism for how HPF protects ribosomes during quiescence.IMPORTANCE The formation of ribosome dimers during periods of dormancy is widespread among bacteria. Dimerization is typically mediated by a single protein, hibernation-promoting factor (HPF). Bacteria lacking HPF exhibit strong defects in viability and pathogenesis and, in some species, extreme loss of rRNA. The mechanistic basis of these phenotypes has not been determined. Here, we report that HPF from the Gram-positive bacterium Bacillus subtilis preserves ribosomes by preventing the loss of essential ribosomal proteins at the dimer interface. This protection may explain phenotypes associated with the loss of HPF, since ribosome protection would aid survival during nutrient limitation and impart a strong selective advantage when the bacterial cell rapidly reinitiates growth in the presence of sufficient nutrients.

Dataset Information

Structural analysis and dimerization potential of the human TAF5 subunit of TFIID.

Publications

Structural analysis and dimerization potential of the human TAF5 subunit of TFIID.

Similar Datasets

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