Molecular cloning and comparative analysis of four beta-galactosidase genes from Bifidobacterium bifidum NCIMB41171.
Bifidobacterium bifidum NCIMB41171 carries four genes encoding different beta-galactosidases. One of them, named bbgIII, consisted of an open reading frame of 1,935 amino acid (a.a.) residues encoding a protein with a multidomain structure, commonly identified on cell wall bound enzymes, having a signal peptide, a membrane anchor, FIVAR domains, immunoglobulin Ig-like and discoidin-like domains. The other three genes, termed bbgI, bbgII and bbgIV, encoded proteins of 1,291, 689 and 1,052 a.a. residues, respectively, which were most probably intracellularly located. Two cases of protein evolution between strains of the same species were identified when the a.a. sequences of the BbgI and BbgIII were compared with homologous proteins from B. bifidum DSM20215. The homologous proteins were found to be differentiated at the C-terminal a.a. part either due to a single nucleotide insertion or to a whole DNA sequence insertion, respectively. The bbgIV gene was located in a gene organisation surrounded by divergently transcribed genes putatively for sugar transport (galactoside-symporter) and gene regulation (LacI-transcriptional regulator), a structure that was found to be highly conserved in B. longum, B. adolescentis and B. infantis, suggesting optimal organisation shared amongst those species.
Department of Food Biosciences, School of Chemistry, Food Biosciences and Pharmacy, The University of Reading, Whiteknights, Reading RG6 6AP, UK. t.goulas@reading.ac.uk
Theodoros K
TK
Goulas
Athanasios K
AK
Goulas
George
G
Tzortzis
Glenn R
GR
Gibson
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001644:Bifidobacterium / Q000201:enzymology* / Q000235:genetics*; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D017434:Protein Structure, Tertiary; D001616:beta-Galactosidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D001616:beta-Galactosidase