A dynamic cpSRP43-Albino3 interaction mediates translocase regulation of chloroplast signal recognition particle (cpSRP)-targeting components.
The chloroplast signal recognition particle (cpSRP) and its receptor, chloroplast FtsY (cpFtsY), form an essential complex with the translocase Albino3 (Alb3) during post-translational targeting of light-harvesting chlorophyll-binding proteins (LHCPs). Here, we describe a combination of studies that explore the binding interface and functional role of a previously identified cpSRP43-Alb3 interaction. Using recombinant proteins corresponding to the C terminus of Alb3 (Alb3-Cterm) and various domains of cpSRP43, we identify the ankyrin repeat region of cpSRP43 as the domain primarily responsible for the interaction with Alb3-Cterm. Furthermore, we show Alb3-Cterm dissociates a cpSRP·LHCP targeting complex in vitro and stimulates GTP hydrolysis by cpSRP54 and cpFtsY in a strictly cpSRP43-dependent manner. These results support a model in which interactions between the ankyrin region of cpSRP43 and the C terminus of Alb3 promote distinct membrane-localized events, including LHCP release from cpSRP and release of targeting components from Alb3.
Lewis
Nathaniel E
NE
Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Marty
Naomi J
NJ
Kathir
Karuppanan Muthusamy
KM
Rajalingam
Dakshinamurthy
D
Kight
Alicia D
AD
Daily
Anna
A
Kumar
Thallapuranam Krishnaswamy Suresh
TK
Henry
Ralph L
RL
Goforth
Robyn L
RL
D029681:Arabidopsis Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D060365:Chloroplast Proteins; D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D006160:Guanosine Triphosphate / Q000737:chemistry; D006868:Hydrolysis; D008954:Models, Biological; D018532:Pisum sativum / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011994:Recombinant Proteins / Q000737:chemistry; D018271:Signal Recognition Particle / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism
C106404:ALBINO 3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060365:Chloroplast Proteins; D011994:Recombinant Proteins; D018271:Signal Recognition Particle; D006160:Guanosine Triphosphate