title: Conserved serine-rich sequences in xylanase and cellulase from Pseudomonas fluorescens subspecies cellulosa: internal signal sequence and unusual protein processing.
abstract: The complete nucleotide sequence of the xynA gene coding for a xylanase (XYLA) expressed by Pseudomonas fluorescens subspecies cellulosa, has been determined. The structural gene consists of an open reading frame of 1833 bp followed by a TAA stop codon. Confirmation of the nucleotide sequence was obtained by comparing the predicted amino acid sequence with that derived by N-terminal analysis of purified forms of the xylanase. The signal peptide present at the N terminus of mature XYLA closely resembles signal peptides of other secreted proteins. Truncated forms of the xylanase gene, in which the sequence encoding the N-terminal signal peptide had been deleted, still expressed coli. XYLA contains domains which are homologous to an endoglucanase expressed by the same organism. These structures include serine-rich sequences. Bal31 deletions of xynA revealed the extent to which these conserved sequences, in XYLA, were essential for xylanase activity. Downstream of the TAA stop codon is a G + C-rich region of dyad symmetry (delta G = 24 kcal) characteristic of E. coli Rho-independent transcription terminators.
authors.affiliation: Department of Agricultural Biochemistry and Nutrition, University of Newcastle upon Tyne, UK.
authors.forename: J
authors.initials: J
authors.lastname: Hall
authors.forename: G P
authors.initials: GP
authors.lastname: Hazlewood
authors.forename: N S
authors.initials: NS
authors.lastname: Huskisson
authors.forename: A J
authors.initials: AJ
authors.lastname: Durrant
authors.forename: H J
authors.initials: HJ
authors.lastname: Gilbert
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002480:Cellulase / Q000235:genetics*; D003001:Cloning, Molecular; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000235:genetics; D011551:Pseudomonas fluorescens / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D012694:Serine; D043325:Xylan Endo-1,3-beta-Xylosidase
chemical_list: D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D012694:Serine; D006026:Glycoside Hydrolases; D043325:Xylan Endo-1,3-beta-Xylosidase; D002480:Cellulase