Complementation of bacterial SecE by a chloroplastic homologue.
The SecE protein is an essential component of the SecAYE-translocase, which mediates protein translocation across the cytoplasmic membrane in bacteria. In the thylakoid membranes of chloroplasts, a protein homologous to SecE, chloroplastic (cp) SecE, has been identified. However, the functional role of cpSecE has not been established experimentally. In this report we show that cpSecE in cells depleted for bacterial SecE (i) supports growth, (ii) stabilizes, just like bacterial SecE, the Sec-translocase core component SecY, and (iii) supports Sec-dependent protein translocation. This indicates that cpSecE can functionally replace bacterial SecE in vivo, and strongly suggests that the thylakoid membrane contains a SecAYE-like translocase with functional and structural similarities to the bacterial complex. This study further underscores the evolutionary link between chloroplasts and bacteria.
Fröderberg
L
L
Department of Biochemistry and Biophysics, Stockholm University, Sweden.
Röhl
T
T
van Wijk
K J
KJ
de Gier
J W
JW
D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D021381:Protein Transport; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C057841:SecY protein, E coli; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins