Article Abstract:
A modified arcDABC operon facilitates the expression of cloned genes in the Pseudomonas aeruginosa for lipase production during oxygen limitation and stationary phase. The arcDABC promoter is modified in the -10 sequence and the -40 region, which is a binding site for the FNR-like anaerobic regulator ANR. Extracellular lipase production increases 30-fold when the modified operon is fused with the P. aeruginosa lipAH gene in an IncQ vector plasmid in semianaerobic cultures. However, severe oxygen limitation inhibits lipase production despite the induction of the ANR-based promoter.
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Article Abstract:
The two major extracellular nuclease isoforms of the bacterium Serratia marcenscens differ in nuclease secretion. One nuclease isoform (Sm2) is secreted by a signal-dependent pathway while the other isoform (Sm1) requires cell lysis for secretion. Sm2 is secreted early and more efficiently than Sm1 when both are synthesized simultaneously, but the efficiency of Sm1 secretion is as good as that of Sm2 when it is produced alone. Therefore, the absence of three amino acids at the N terminal end in Sm1 has no association with its poor secretion efficiency.
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Article Abstract:
The lipase from Serratia marcescens is contained in extracellular enzyme protein group secreted by the class I secretion pathway, and is purified from the supernatant culture possessing a lipase expression vector. When a 2.8-kb SalI subunit is subcloned in a plasmid and the lipase is expressed in Escherichia coli, the extracellular lipase is identified in the presence of the secretion plasmid pGSD6. The lipase-specific consensus sequence G-X1-S-X2-G is present in the amino-terminal part of the protein.
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