Efficient interaction between two GTPases allows the chloroplast SRP pathway to bypass the requirement for an SRP RNA.

ABSTRACT: Cotranslational protein targeting to membranes is regulated by two GTPases in the signal recognition particle (SRP) and the SRP receptor; association between the two GTPases is slow and is accelerated 400-fold by the SRP RNA. Intriguingly, the otherwise universally conserved SRP RNA is missing in a novel chloroplast SRP pathway. We found that even in the absence of an SRP RNA, the chloroplast SRP and receptor GTPases can interact efficiently with one another; the kinetics of interaction between the chloroplast GTPases is 400-fold faster than their bacterial homologues, and matches the rate at which the bacterial SRP and receptor interact with the help of SRP RNA. Biochemical analyses further suggest that the chloroplast SRP receptor is pre-organized in a conformation that allows optimal in

SUBMITTER: Jaru-Ampornpan P 

PROVIDER: S-EPMC1924832 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature