Expression studies of two paralogous ppa genes encoding distinct Family I pyrophosphatases in marine unicellular cyanobacteria reveal inactivation of the typical cyanobacterial gene.
Genome sequence analyses revealed the occurrence of two paralogous ppa genes potentially encoding distinct Family I inorganic pyrophosphatases (sPPases, EC3.6.1.1) in the marine unicellular cyanobacteria Prochlorococcus marinus strains MED4 and MIT9313 and Synechococcus sp. WH8102. Protein sequence alignment and phylogenetic analysis indicated that the ppa gene proper of cyanobacteria (ppa1) encodes a presumably inactive mutant enzyme whereas the second gene (ppa2) might encode an active sPPase closely related to those of some proteobacteria. Heterologous expression of the two cloned P. marinus MED4 ppa genes in Escherichia coli confirmed this proposal, only the inactive ppa1 product being immunodetected by anti-cyanobacterial sPPase antibodies. A possible scenario of ppa gene inactivation and replacement in the context of the postulated rapid diversification of marine unicellular cyanobacteria, the most abundant photosynthetic prokaryotes in the oceans, is discussed.
Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Avda. Américo Vespucio s/n, Seville, Spain.
María R
MR
Gómez-García
Aurelio
A
Serrano
D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000201:enzymology*; D004247:DNA / Q000378:metabolism; D019143:Evolution, Molecular; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids / Q000378:metabolism; D011755:Pyrophosphatases / Q000096:biosynthesis* / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D004247:DNA; D011755:Pyrophosphatases