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Analysis of a novel gene and beta-galactosidase isozyme from a psychrotrophic Arthrobacter isolate.

ABSTRACT: We have characterized a new psychrotrophic Arthrobacter isolate which produces beta-galactosidase isozymes. When DNA from this isolate was transformed into an Escherichia coli host, we obtained three different fragments, designated 12, 14, and 15, each encoding a different beta-galactosidase isozyme. The beta-galactosidase produced from fragment 12 was of special interest because the protein subunit was smaller (about 71 versus 116 kDa) than those typically encoded by the lacZ family. The isozyme encoded by fragment 12 was purified, and its activity and thermostability were examined. Although the enzyme is highly specific towards beta-D-galactoside substrates, its levels in the isolate do not increase in cells grown with lactose. Nucleotide sequence determination showed that the gene encoding isozyme 12 is not similar to the other members of the lacZ family but has regions similar to beta-galactosidase isozymes from Bacillus stearothermophilus and B. circulans. Addition of the isozyme 12 sequence to the database made it possible to examine these enzymes as possible members of a new, separate family. Our analysis of this new family showed some conserved amino acids corresponding to the lacZ acid-base catalytic region but no homology with the nucleophilic region. On the basis of these comparisons, we designated this a new lacG family.

SUBMITTER: Gutshall KR

PROVIDER: S-EPMC176839 | biostudies-other | 1995 Apr

REPOSITORIES: biostudies-other

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Analysis of a novel gene and beta-galactosidase isozyme from a psychrotrophic Arthrobacter isolate.

Gutshall K R KR Trimbur D E DE Kasmir J J JJ Brenchley J E JE

Journal of bacteriology 19950401 8

We have characterized a new psychrotrophic Arthrobacter isolate which produces beta-galactosidase isozymes. When DNA from this isolate was transformed into an Escherichia coli host, we obtained three different fragments, designated 12, 14, and 15, each encoding a different beta-galactosidase isozyme. The beta-galactosidase produced from fragment 12 was of special interest because the protein subunit was smaller (about 71 versus 116 kDa) than those typically encoded by the lacZ family. The isozym ...[more]

PMID: 7721689

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Project description:In the cold regions of China, lignin-rich corn straw accumulates at high levels due to low temperatures. The application of psychrotrophic lignin-degrading bacteria should be an effective means of overcoming the low-temperature limit for lignin degradation and promoting the utilization of corn straw. However, this application is limited by the lack of suitable strains for decomposition of lignin; furthermore, the metabolic mechanism of psychrotrophic lignin-degrading bacteria is unclear. Here, the whole genome of the psychrotrophic lignin-degrading bacterium Arthrobacter sp. C2, isolated in our previous work, was sequenced. Comparative genomics revealed that C2 contained unique genes related to lignin degradation and low-temperature adaptability. DyP may participate in lignin degradation and may be a cold-adapted enzyme. Moreover, DyP was proven to catalyze lignin Cα-Cβ bond cleavage. Deletion and complementation of the DyP gene verified its ability to catalyze the first-step reaction of lignin degradation. Comparative transcriptomic analysis revealed that the transcriptional expression of the DyP gene was upregulated, and the genetic compensation mechanism allowed C2ΔDyP to degrade lignin, which provided novel insights into the survival strategy of the psychrotrophic mutant strain C2ΔdyP. This study improved our understanding of the metabolic mechanism of psychrotrophic lignin-degrading bacteria and provided potential application options for energy-saving production using cold-adapted lignin-degrading enzymes. Graphical Abstract The psychrotrophic lignin-degrading Arthrobacter sp. C2 strain exhibited lignin degradation ability and low temperature adaptability. The cold-adapted DyP enzyme of C2 was involved in the catalytic cleavage of lignin Cα-Cβ bonds as a key lignin-degrading enzyme. Comparative transcriptomic analysis showed that the induced transcriptional expression of DyP genes increased on lignin medium, and the mechanism of genetic compensation explained the survival strategy of the mutant strain C2ΔDyP.

Dataset Information

Analysis of a novel gene and beta-galactosidase isozyme from a psychrotrophic Arthrobacter isolate.

Publications

Analysis of a novel gene and beta-galactosidase isozyme from a psychrotrophic Arthrobacter isolate.

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