Dataset Information

Screening for Type II L-Asparaginases: Lessons from the Genus Halomonas.

ABSTRACT: Among the two types of bacterial L-asparaginases, only type II enzymes have been used in the treatment of acute lymphoblastic leukemia owing to their higher affinity for L-asparagine. However, current screening media used for the isolation of L-asparaginase-producing microorganisms do not discriminate between the two types of L-asparaginase. During an optimization study conducted to increase L-asparaginase production by environmental Halomonas isolates, it was noticed that the pattern of L-asparaginase production in response to variations in glucose concentration varied between different isolates suggesting that they differ in their ability to produce type II L-asparaginases, an observation that was confirmed by further experiments. Bioinformatics analysis of available Halomonas whole genome sequences revealed that indeed some species of this genus possess both L-asparaginase types while others possess only type I enzymes. By comparing the growth pattern of these isolates on different media, we propose that by omitting glucose, reducing the concentration of L-asparagine and providing an alternative nitrogen source in L-asparaginase screening media it may be possible to differentiate between type I and type II activities.

SUBMITTER: Sharafi Z

PROVIDER: S-EPMC5843318 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Screening for Type II L-Asparaginases: Lessons from the Genus <i>Halomonas</i>.

Sharafi Zeinab Z Barati Mahmood M Khoshayand Mohammad Reza MR Adrangi Sina S

Iranian journal of pharmaceutical research : IJPR 20170101 4

Among the two types of bacterial L-asparaginases, only type II enzymes have been used in the treatment of acute lymphoblastic leukemia owing to their higher affinity for L-asparagine. However, current screening media used for the isolation of L-asparaginase-producing microorganisms do not discriminate between the two types of L-asparaginase. During an optimization study conducted to increase L-asparaginase production by environmental <i>Halomonas</i> isolates, it was noticed that the pattern of ...[more]

PMID: 29552065

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Project description:BACKGROUND:Species of the genus Halomonas are salt-tolerant organisms that have a versatile metabolism and can degrade a variety of xenobiotic compounds, utilizing them as their sole carbon source. In this study, we examined the genome of a Halomonas isolate from a hydrocarbon-contaminated site to search for chemosensory genes that might be responsible for the observed chemotactic behavior of this organism as well as for other responses to environmental cues. RESULTS:Using genome-wide comparative tools, our isolate was identified as a strain of Halomonas titanicae (strain KHS3), together with two other Halomonas strains with available genomes that had not been previously identified at a species level. The search for the main components of chemosensory pathways resulted in the identification of two clusters of chemosensory genes and a total of twenty-five chemoreceptor genes. One of the gene clusters is very similar to the che cluster from Escherichia coli and, presumably, it is responsible for the chemotactic behavior towards a variety of compounds. This gene cluster is present in 47 out of 56 analyzed Halomonas strains with available genomes. A second che-like cluster includes a gene coding for a diguanylate cyclase with a phosphotransfer and two receiver domains, as well as a gene coding for a chemoreceptor with a longer cytoplasmic domain than the other twenty-four. This seemingly independent pathway resembles the wsp pathway from Pseudomonas aeruginosa although it also presents several differences in gene order and domain composition. This second chemosensory gene cluster is only present in a sub-group within the genus Halomonas. Moreover, remarkably similar gene clusters are also found in some orders of Proteobacteria phylogenetically more distant from the Oceanospirillales, suggesting the occurrence of lateral transfer events. CONCLUSIONS:Chemosensory pathways were investigated within the genus Halomonas. A canonical chemotaxis pathway, controlled by a variable number of chemoreceptors, is widespread among Halomonas species. A second chemosensory pathway of unique organization that involves some type of c-di-GMP signaling was found to be present only in one branch of the genus, as well as in other proteobacterial lineages.

Dataset Information

Screening for Type II L-Asparaginases: Lessons from the Genus Halomonas.

Publications

Screening for Type II L-Asparaginases: Lessons from the Genus <i>Halomonas</i>.

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