High impact information on RPB5

• The Saccharomyces cerevisiae genes that encode these subunits (RPB5, RPB6, and RPB8) were isolated and sequenced, and their transcriptional start sites were deduced [1].
• Four subunits that are common to pol I, II, and III (ABC27, ABC14.5, ABC10alpha, and ABC10beta), two that are common to pol I and III (AC40 and AC19), and one pol III-specific subunit (C11) can associate with defined regions of the two large subunits [2].
• We demonstrate that RPB5 and the RPB1-CTD have overlapping roles in activation because the double mutant is synthetically lethal and has exacerbated activation defects at the GAL1/10 promoter [3].
• In vivo experiments using inducible reporter plasmids and Northern analysis support the in vitro data and demonstrate that RPB5 influences activation at some, but not all, promoters [3].
• Mutations in the C terminus of Rsc4 conferred a thermosensitive phenotype and the loss of interaction with Rpb5 [4].

Biological context of RPB5

• The polypeptide predicted from DNA sequence of the rpb5+ gene consists of 210 amino acids with a calculated molecular weight of 23914 [5].
• This polypeptide has a predicted pI of 9.6, matches 14 of 16 amino acids in the amino terminus of cauliflower RPB5 that was microsequenced, and shows 42 and 53% amino acid sequence identity with the yeast and human RPB5 subunits, respectively [6].
• In addition to the already known gene RPB5, coding for a subunit shared by all three DNA directed RNA polymerases, two new open reading frames could be identified [7].
• Here we report on the sequence and functional analysis of a 7217 bp fragment located on the right arm of chromosome II between RPB5 and CDC28 [8].

Physical interactions of RPB5

• Rpb5 was found to interact with any fragment of Rpb1 that contained the region H, which is conserved among the subunit 1 homologues of all RNA polymerases, including the beta' subunit of prokaryotic RNA polymerases [9].
• In agreement with the fact that Rpb5 is shared among all three forms of eukaryotic RNA polymerases, the region H of RNA polymerase I subunit 1 (Rpa190) was also found to interact with Rpb5 [9].

Other interactions of RPB5

• Only recently has it been suggested that besides the largest subunit of RNA polymerase II, smaller subunits like Rpb3 and Rpb5 may have regulatory roles in expression of specific sets of genes [10].

Analytical, diagnostic and therapeutic context of RPB5

• Crystallization and preliminary diffraction studies of the RNA polymerase subunit RPB5 from Saccharomyces cerevisiae [11].
• Lethal or conditional mutants of the C-terminal globe altered the binding of Rpb5 to Rpb1-beta25/26 (prolonging the Bridge helix) and Rpb1-alpha44/47 (ahead of the Switch 1 loop and binding Rpb5 in a two-hybrid assay) [12].

References