Functional importance of the oligomer formation of the cyanobacterial H⁺ pump Gloeobacter rhodopsin.

ABSTRACT: Many microbial rhodopsins self-oligomerize, but the functional consequences of oligomerization have not been well clarified. We examined the effects of oligomerization of a H⁺ pump, Gloeobacter rhodopsin (GR), by using nanodisc containing trimeric and monomeric GR. The monomerization did not appear to affect the unphotolyzed GR. However, we found a significant impact on the photoreaction: The monomeric GR showed faint M intermediate formation and negligible H⁺ transfer reactions. These changes reflected the elevated pKa of the Asp121 residue, whose deprotonation is a prerequisite for the functional photoreaction. Here, we focused on His87, which is a neighboring residue of Asp121 and conserved among eubacterial H⁺ pumps but replaced by Met in an archaeal H<

SUBMITTER: Iizuka A 

PROVIDER: S-EPMC6656774 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature