• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.400-405
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• 2003

A gene (hpkA), encoding a histidine protein kinase homolog, has been identified in the upstream region of the espAB operon in Myxococcus xanthus. It encodes a 333 amino acid (35,952 Da) protein with a histidine protein kinase domain in the region from amino acid 90 to 317. Null mutations in the hpkA gene caused formation of loose irregular fruiting bodies, while wild-type strains developed tight hemispherical fruiting bodies under developmental conditions. Sporulation of the hpkA mutant was delayed by at least 12 h compared to that of the wild-type. It appeared that the hpkA mutation increased the expression of the espAB operon by more than 2-fold compared with the wild-type under developmental conditions. Expression of the hpkA gene was low under vegetative conditions, but was highly induced under developmental conditions.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.771-777
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• 2006

A novel gene (agiA) required for adventurous gliding motility in Myxococcus xanthus has been identified. Null mutations in this gene caused defects in the gliding movement of isolated cells, suggesting that it belongs to one of the A-motility genes. The isolated agiA mutant cells neither glided nor produced slime trails on agar surface. However, agiA was different from other known A-motility genes in that the agiA mutant created in the $S^-$ mutant background glided in the swarm of cells, since other known A-motility mutants created in the $S^-$ mutant background do not move in the swarm of cells. The agiA mutant was also defective in fruiting body development. Sequence analysis predicted that agiA encodes a 787-amino-acid protein with eight tripeptide repeat motifs.

• Journal of Microbiology and Biotechnology
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• 제19권11호
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• pp.1288-1294
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• 2009

We have used mutational analysis to identity four genes, MXAN3553, MXAN3554, MXAN3555, and MXAN3556, constituting an operon that is essential for normal fruiting body development in Myxococcus xanthus. Deletion of MXAN3553, which encoded a hypothetical protein, resulted in delayed fruiting body development. MXAN3554 was predicted to encode a metallopeptidase, and its deletion caused fruiting body formation to fail. Inactivation of MXAN3555, which encoded a putative NtrC-type response regulator, resulted in delayed aggregation and a severe reduction in sporulation. Fruiting bodies also failed to develop with the deletion of MXAN3556, another gene encoding a hypothetical protein.

• 생명과학회지
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• 제13권6호
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• pp.814-821
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• 2003

Heme 합성의 중간체이며 또한 광수용체로도 작용하는 protoporphyrin IX의 세포 내 농도 및 성장 배지에 존재하는 농도가 야생형 M. xanthus DK1622 균주로부터 측정되었다. Protoporphyrin IX의 세포 내 농도는 배양 시간이 경과함에 따라 계속 증가하여, 안정기에 최고치에 이르는 것으로 나타났다 안정기에 도달한 세포 내에는 6.4 picomoles/mg of protein의 protoporphrin IX이 존재하는 것으로 밝혀졌다. Protoporphyrin IX은 대수기 중간 시기부터 세포외로 분비가 시작되어, 안정기에 도달한 세포의 배양액에서는 세포의 단백질 대비하여 3.0 picomoles/mg of protein이 존재하는 것으로 측정되었다. 영양분의 고갈에 기인하여 형성된 포자에서도 protoporphyrin IX의 농도는 6.5 picomoles/mg of protein이 존재하는 것으로 관찰되었다. Succinylacetone을 $500\muM$ 농도로 성장 배지에 첨가하였을 경우에 protoporphyrin IX의 생산은 검출이 불가능할 정도로 방해를 받았으며, 세포성장이 저해되고 세포 성장은 정상의 절반 수준인 약 100 Klett unit에서 정지하는 것으로 나타났다. 하지만 포자의 형성은 succinylacetone의 첨가에 관계없이 89-100%의 생성율을 보였음으로 정상 농도의 protoporphyrin IX가 M. xanthus의 성장을 위해서는 중요하지만, 포자 형성 과정에 필수적인 것으로 보이지는 않는다. 안정기 세포에서 나타나는 photolysis 현상도 succinylacetone의 첨가 여부에 관계없이 유사한 수준으로 관찰되었다.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.51-54
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• 2009

Myxobacteria, Gram-negative soil bacteria, are a well-known producer of bioactive secondary metabolites. Therefore, this study presents a methodological approach for the high-throughput screening of secondary metabolites from 4 wild-type Myxococcus xanthus strains. First, electrospray ionization mass spectrometry (ESI-MS) was performed using extracellular crude extracts. As a result, 22 metabolite peaks were detected, and the metabolite profiling was then conducted using the m/z value, retention time, and MS/MS fragmentation pattern analyses. Among the peaks, one unknown compound peak was identified as analogous to the myxalamid A, B, and C series. An analysis of the tandem mass spectrometric fragmentation patterns and HR-MS identified myxalamid K as a new compound derived from M. xanthus. In conclusion, LC-MS/MS-based chemical screening of diverse secondary metabolites would appear to be an effective approach for discovering unknown microbial secondary metabolites.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1998년도 한국생물과학협회 학술발표대회
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• pp.331.2-331
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• 1998

No Abstract, See Full Text

• Journal of Microbiology and Biotechnology
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• 제31권7호
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• pp.912-920
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• 2021

SOS response is a conserved response to DNA damage in prokaryotes and is negatively regulated by LexA protein, which recognizes specifically an "SOS-box" motif present in the promoter region of SOS genes. Myxococcus xanthus DK1622 possesses a lexA gene, and while the deletion of lexA had no significant effect on either bacterial morphology, UV-C resistance, or sporulation, it did delay growth. UV-C radiation resulted in 651 upregulated genes in M. xanthus, including the typical SOS genes lexA, recA, uvrA, recN and so on, mostly enriched in the pathways of DNA replication and repair, secondary metabolism, and signal transduction. The UV-irradiated lexA mutant also showed the induced expression of SOS genes and these SOS genes enriched into a similar pathway profile to that of wild-type strain. Without irradiation treatment, the absence of LexA enhanced the expression of 122 genes that were not enriched in any pathway. Further analysis of the promoter sequence revealed that in the 122 genes, only the promoters of recA2, lexA and an operon composed of three genes (pafB, pafC and cyaA) had SOS box sequence to which the LexA protein is bound directly. These results update our current understanding of SOS response in M. xanthus and show that UV induces more genes involved in secondary metabolism and signal transduction in addition to DNA replication and repair; and while the canonical LexA-dependent regulation on SOS response has shrunk, only 5 SOS genes are directly repressed by LexA.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1068-1077
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• 2018

DKxanthenes are a class of yellow secondary metabolites produced by myxobacterial genera Myxococcus and Stigmatella. We identified a putative 49.5 kb DKxanthene biosynthetic gene cluster from Myxococcus stipitatus DSM 14675 by genomic sequence and mutational analyses. The cluster consisted of 15 genes (MYSTI_06004-MYSTI_06018) encoding polyketide synthases, non-ribosomal peptide synthases, and proteins with unknown functions. Disruption of the genes by plasmid insertion resulted in defects in the production of yellow pigments. High-performance liquid chromatography and liquid chromatography-tandem mass spectrometry analyses indicated that the yellow pigments produced by M. stipitatus DSM 14675 might be novel DKxanthene derivatives. M. stipitatus did not require DKxanthenes for the formation of heat-resistant viable spores, unlike Myxococcus xanthus. Furthermore, DKxanthenes showed growth inhibitory activity against the fungi Aspergillus niger, Candida albicans, and Rhizopus stolonifer.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2002년도 제35회 학술심포지움 및 춘계학술대회
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• pp.49-49
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• 2002

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2002년도 제35회 학술심포지움 및 춘계학술대회
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• pp.50-50
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• 2002