Transcriptional regulation and signal-peptide-dependent secretion of exolevanase (LsdB) in the endophyte Gluconacetobacter diazotrophicus.
Gluconacetobacter diazotrophicus utilizes plant sucrose with a constitutively expressed levansucrase (LsdA), producing extracellular levan, which may be degraded under energetically unfavored conditions. Reverse transcriptase-PCR analysis revealed that lsdA and the downstream exolevanase gene (lsdB) form an operon. lsdB transcription was induced during growth with low fructose concentrations (0.44 to 33 mM) and repressed by glucose. Transport of LsdB to the periplasm involved N-terminal signal peptide cleavage. Type II secretion mutants failed to transfer LsdB across the outer membrane, impeding levan hydrolysis.
Menéndez
Carmen
C
Laboratorio Interacciones Planta-Microorganismos, Centro de Ingeniería Genética y Biotecnología, Apartado 6162, Habana 10600, Cuba.
Banguela
Alexander
A
Caballero-Mellado
Jesús
J
Hernández
Lázaro
L
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D005630:Fructans / Q000378:metabolism; D005632:Fructose / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D041821:Gluconacetobacter / Q000201:enzymology* / Q000235:genetics*; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009876:Operon; D019897:Periplasm / Q000201:enzymology; D021382:Protein Sorting Signals; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D005630:Fructans; D021382:Protein Sorting Signals; D005632:Fructose; D006026:Glycoside Hydrolases; C021512:levanase; D005947:Glucose