title: Cyanobacterial alkaline/neutral invertases. Origin of sucrose hydrolysis in the plant cytosol?
abstract: The aim of this work was to investigate the occurrence of invertase (Inv) in cyanobacteria. We describe the first isolation and characterization of prokaryotic alkaline/neutral Inv (A/N-Inv) genes. Two genes (invA and invB) were identified in Anabaena sp. PCC 7120, which share about 50-56% identity with plant A/N-Inv and encode proteins of about 53-55 kDa. The identification of these proteins was confirmed by biochemical and immunological studies with recombinant proteins and with the enzymes isolated from Anabaena cells. Expression analysis supported the important role of A/N-Inv in nitrogen-fixing growth conditions. Nevertheless, A/N-Inv activities were shown in all filamentous and unicellular cyanobacteria investigated, regardless of their capacity to fix dinitrogen. Searches in complete sequenced genomes showed that A/N-Inv homologues are restricted to cyanobacterial species and plants. In particular, filamentous nitrogen-fixing strains display two A/N-Inv genes and unicellular strains have only one. Phylogenetic analysis leads us to suggest that modern plant A/N-Inv might have originated from an orthologous ancestral gene after the endosymbiotic origin of chloroplasts.
authors.affiliation: Centro de Investigaciones Biológicas, Fundación para Investigaciones Biológicas Aplicadas, 7600 C.C. 1348, Mar del Plata, Argentina.
authors.forename: Walter
authors.initials: W
authors.lastname: Vargas
authors.forename: Andrea
authors.initials: A
authors.lastname: Cumino
authors.forename: Graciela L
authors.initials: GL
authors.lastname: Salerno
mesh_terms: D000595:Amino Acid Sequence; D017033:Anabaena / Q000201:enzymology* / Q000235:genetics; D003600:Cytosol / Q000378:metabolism* / Q000382:microbiology; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000502:physiology; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D010802:Phylogeny; D010944:Plants / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013395:Sucrose / Q000378:metabolism*; D043324:beta-Fructofuranosidase
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger; D013395:Sucrose; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase; D009584:Nitrogen