The Chloroplast SRP Systems of Chaetosphaeridium globosum and Physcomitrella patens as Intermediates in the Evolution of SRP-Dependent Protein Transport in Higher Plants.

ABSTRACT: The bacterial signal recognition particle (SRP) mediates the cotranslational targeting of membrane proteins and is a high affinity complex consisting of a SRP54 protein subunit (Ffh) and an SRP RNA. The chloroplast SRP (cpSRP) pathway has adapted throughout evolution to enable the posttranslational targeting of the light harvesting chlorophyll a/b binding proteins (LHCPs) to the thylakoid membrane. In spermatophytes (seed plants), the cpSRP lacks the SRP RNA and is instead formed by a high affinity interaction of the conserved 54-kD subunit (cpSRP54) with the chloroplast-specific cpSRP43 protein. This heterodimeric cpSRP recognizes LHCP and delivers it to the thylakoid membrane. However, in contrast to spermatophytes, plastid SRP RNAs were identified within all streptophyte lineages and in

SUBMITTER: Ziehe D 

PROVIDER: S-EPMC5115805 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature