Characterization of a cDNA encoding the thylakoidal processing peptidase from Arabidopsis thaliana. Implications for the origin and catalytic mechanism of the enzyme.
We have identified and sequenced a cDNA containing a complete open reading frame for a putative 340-amino acid precursor of the thylakoidal processing peptidase from Arabidopsis thaliana. The predicted amino acid sequence of the protein includes regions highly conserved among Type I leader peptidases and indicates that the enzyme uses a serine-lysine catalytic dyad mechanism. Phylogenetic analysis indicated a common ancestry of the enzyme with those from oxygenic photosynthetic prokaryotes, suggesting that the cDNA encoded the chloroplast enzyme. The catalytic domain was overexpressed in Escherichia coli, generating a product capable of cleaving the thylakoid-transfer domain from a chloroplast protein. Antibodies to the overexpressed polypeptide cross-reacted with a 30-kDa thylakoid membrane protein.
Chaal
B K
BK
Cambridge Center for Molecular Recognition, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom.
Mould
R M
RM
Barbrook
A C
AC
Gray
J C
JC
Howe
C J
CJ
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D002384:Catalysis; D018076:DNA, Complementary; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D010450:Endopeptidases; C069654:thylakoid processing peptidase