Conserved Trigger Loop Histidine of RNA Polymerase II Functions as a Positional Catalyst Primarily through Steric Effects.

ABSTRACT: In all domains of life, multisubunit RNA polymerases (RNAPs) catalyze both the extension of mRNA transcripts by nucleotide addition and the hydrolysis of RNA, which enables proofreading by removal of misincorporated nucleotides. A highly conserved catalytic module within RNAPs called the trigger loop (TL) functions as the key controller of these activities. The TL is proposed to act as a positional catalyst of phosphoryl transfer and transcript cleavage via electrostatic and steric contacts with substrates in its folded helical form. The function of a near-universally conserved TL histidine that contacts NTP phosphates is of particular interest. Despite its exceptional conservation, substitutions of the TL His with Gln support efficient catalysis in bacterial and yeast RNAPs. Unlike bacter

SUBMITTER: Palo MZ 

PROVIDER: S-EPMC9066048 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature