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Title: CLONING OF CELLOBIOSE UTILIZATION GENES FROM G- AND G+ BACTERIA: FUNCTIONAL EXPRESSION IN ESCHERICHIA COLI

Author
item LAI, XAI - UNIV FL
item INGRAM, LONNIE - UNIV FL
item Hespell, Robert

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Previous studies in our lab have shown that in Bacillus stearothermophilus cellobiose uptake occurs via a phosphoenolpyruvate-dependent transport system (PTS). Although the B. stearothermophilus genes for uptake and cleavage were expressed in E. coli, levels were insufficient to support growth on cellobiose. Nine additional gene libraries have now been screened for cellobiose utilization systems which function in E. coli. Active clones were isolated from B. subtilis, Butyrivibrio fibrisolvens, and Klebsiella oxytoca. Clones with lower activities were isolated from B. coagulans, K. planricola, and Streptococcus bovis. Activities encoded by all of these clones were dependent upon functional ptsH and ptsI products in the host, indicating that all are PTS operons. No functional cellobiose utilization systems were recovered from libraries of Clostridium thermocellum, Bacteroides ruminicola, or Selenomonas ruminantium. Sequencing of the K. oxytoca cel operon revealed that EII**CEL is composed of a single polypeptide, rather than three separate subunits as found in other cel operons. Predicted protein sequences for EII**CEL and the phosphocellobiase shared limited homology with E. coli or B. stearothermophilus cel operon products, but were similar to the Erwinia chrysanthemi PTS proteins involved in arbutin and salicin (arb) metabolism (nonfunctional with cellobiose). Based on these studies, we conclude that PTS systems for cellobiose are widespread among cellobiose-utilizing G+ and G-, aerobic and obligately anaerobic bacteria. Differences observed among the cel gene products suggest the possibility of multiple evolutionary origins.