PUL ID

PUL0402

PubMed

11282589, Appl Environ Microbiol. 2001 Apr;67(4):1445-52. doi: 10.1128/AEM.67.4.1445-1452.2001.

Characterization method

Northern Blot,enzyme activity assay

Genomic accession number

AP012281

Nucelotide position range

1563593-1571798

Substrate

xylan,xylose

Loci

lilo_1425-lilo_1430

Species

Lactococcus lactis subsp. lactis IO-1/1046624

Degradation or Biosynthesis

degradation

Gene Name

Locus Tag

Protein ID

Gene Position

GenBank Contig Range

EC Number

xynB lilo_1425 BAL51422.1 0 - 1680 (-) AP012281.1:1563593-1565273 -
xynT lilo_1426 BAL51423.1 1704 - 3189 (-) AP012281.1:1565297-1566782 -
xylM lilo_1427 BAL51424.1 3243 - 4248 (-) AP012281.1:1566836-1567841 -
xylB lilo_1428 BAL51425.1 4250 - 5756 (-) AP012281.1:1567843-1569349 -
xylA lilo_1429 BAL51426.1 5822 - 7142 (-) AP012281.1:1569415-1570735 -
xylR lilo_1430 BAL51427.1 7246 - 8206 (+) AP012281.1:1570839-1571799 -

Cluster number

1

Gene name

Gene position

Gene type

Found by CGCFinder?

xynB 1 - 1680 (-) CAZyme: GH43_11|GH43 Yes
xynT 1705 - 3189 (-) TC: gnl|TC-DB|P94488|2.A.2.3.2 Yes
xylM 3244 - 4248 (-) CDS No
xylB 4251 - 5756 (-) CDS No
xylA 5823 - 7142 (-) CDS No
xylR 7247 - 8206 (+) TF: DBD-Pfam|HTH_AraC,DBD-Pfam|HTH_AraC,DBD-SUPERFAMILY|0036286,DBD-SUPERFAMILY|0035607 No

PUL ID

PUL0402

PubMed

11282589, Appl Environ Microbiol. 2001 Apr;67(4):1445-52. doi: 10.1128/AEM.67.4.1445-1452.2001.

Title

Genetic evidence for a defective xylan degradation pathway in Lactococcus lactis.

Author

Erlandson KA, Delamarre SC, Batt CA

Abstract

Genetic and biochemical evidence for a defective xylan degradation pathway was found linked to the xylose operon in three lactococcal strains, Lactococcus lactis 210, L. lactis IO-1, and L. lactis NRRL B-4449. Immediately downstream of the xylulose kinase gene (xylB) (K. A. Erlandson, J.-H. Park, W. El Khal, H.-H. Kao, P. Basaran, S. Brydges, and C. A. Batt, Appl. Environ. Microbiol. 66:3974-3980, 1999) are two open reading frames encoding a mutarotase (xylM) and a xyloside transporter (xynT) and a partial open reading frame encoding a beta-xylosidase (xynB). These are functions previously unreported for lactococci or lactobacilli. The mutarotase activity of the putative xylM gene product was confirmed by overexpression of the L. lactis enzyme in Escherichia coli and purification of recombinant XylM. We hypothesize that the mutarotase links xylan degradation to xylose metabolism due to the anomeric preference of xylose isomerase. In addition, Northern hybridization experiments suggested that the xylM and xynTB genes are cotranscribed with the xylRAB genes, responsible for xylose metabolism. Although none of the three strains appeared to metabolize xylan or xylobiose, they exhibited xylosidase activity, and L. lactis IO-1 and L. lactis NRRL B-4449 had functional mutarotases.