The gene encoding UDP-glucose pyrophosphorylase is required for the synthesis of xanthan gum in Xanthomonas campestris.
Xanthomonas campestris pv. campestris produces a large quantity of exopolysaccharide, xanthan gum, rendering the colonies mucoid. G76E was a non-mucoid mutant isolated from Xc17 by Tn5 mutagenesis. A 3.0-kb KpnI-EcoRI fragment from the Xc17 chromosome was able to restore mucoid phenotype to G76E. Sequence analysis of the region responsible for the restoration revealed an open reading frame, ORF324, able to encode a polypeptide of 35,232 Da which shows striking similarity to the UDP-glucose pyrophosphorylases from bacteria. The activity of UDP-glucose pyrophosphorylase reduced drastically in G76E was found to be regained in the presence of the cloned 3.0-kb KpnI-EcoRI fragment. In vitro expression of the gene in the S30 transcription/translation system produced a protein of ca. 35 kDa.
Wei
C L
CL
Department of Botany, National Chung Hsing University, Taichung, Taiwan.
Lin
N T
NT
Weng
S F
SF
Tseng
Y H
YH
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005798:Genes, Bacterial; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D016962:Sinorhizobium meliloti / Q000201:enzymology; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016959:Xanthomonas campestris / Q000201:enzymology* / Q000235:genetics
D011135:Polysaccharides, Bacterial; D011994:Recombinant Proteins; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; C002563:xanthan gum