Proteasome‐mediated degradation of TATA binding protein (TBP2) in Haloferax volcanii (556.1)

Abstract

Gene transcription and proteolysis are two processes that have seemingly nothing in common: transcription is the first step in the life of any protein and proteolysis is last. However, we show that TATA binding protein (TBP2), one of the general transcription factors in Haloferax volcanii is degraded in proteasome‐mediated way. To be specific, TBP2 levels are increased by either chemical inhibition or genetic depletion of catalytic 20S core particles of proteasomes. In addition, TBP2 levels are higher in AAA+ ATPases proteasome‐activating nucleotidase (PAN) and cell division cycle 48 (cdc48) mutant strains compared with wild‐type strain suggesting TPB2 turnover by proteasome also requires AAA+ ATPases which closely related to the regulatory particle triple‐A ATPases (Rpt) of eukaryotic 26S proteasomes. Interestingly, like ubiquitin‐proteasome system in eukaryotic the recent described small ubiquitin‐like archaeal modifier proteins (SAMPs), its activating enzyme, E1 like UbaA, and the potential de‐ubiquitin enzyme (JAMM2) seem to be involved in TBP2 degradation based on the fact TBP2 level are much higher in those mutant strains than wild‐type strain, although evidences also suggest the presence of a SAMP‐independent pathway for TBP2 degradation. Overall, these findings first open a window for disclosing interactions among transcription initiation, SAMP and proteasome systems in archaea.Grant Funding Source: NIH R01 GM057498 and DOE DE‐FG02‐05ER15650