• Journal of Microbiology and Biotechnology
• /
• 제25권6호
• /
• pp.771-781
• /
• 2015

To examine if the molecular chaperone DnaK operon proteins of Streptococcus suis type 2 (SS2) are involved in adhesion to host cells, the abundance values of these proteins from the surface of two SS2 strains of different adhesion capability were compared. Their roles in growth and adhesion to human laryngeal epithelial cell line HEp-2 cells were investigated on SS2 strain HA9801 and its mutants with DnaK operon genes partially knocked-out (PKO mutant) under heat stress. The major difference was that DnaJ was more abundant in strain HA9801 than in strain JX0811. Pretreatment of the bacteria with hyperimmune sera to DnaJ, but not with those to other proteins, could significantly reduce SS2 adhesion to HEp-2 cells. PKO of dnaJ g ene resulted in decreased SS2 growth at 37℃ and 42℃, and reduced its adhesion to HEp-2 cells. The wild-type strain stressed at 42℃ had increased expression of DnaJ on its surface and elevated adhesion to HEp-2 cells, which was also inhibitable by DnaJ specific antiserum. These results indicate that the DnaJ of S. suis type 2 is important not only for thermotolerance but also for adhesion to host cells. Because DnaJ expression is increased upon temperature upshift with increased exposure on the bacterial surface, the febrile conditions of the cases with systemic infections might help facilitate bacterial adhesion to host cells. DnaJ could be one of the potential candidates as a subunit vaccine because of its good immunogenicity.

• Journal of Microbiology and Biotechnology
• /
• 제23권11호
• /
• pp.1519-1528
• /
• 2013

Bacillus pumilus SG2, a halotolerant strain, expresses two major chitinases designated ChiS and ChiL that were induced by chitin and secreted into the supernatant. The present work aimed to obtain a mutant with higher chitinolytic activity through mutagenesis of Bacillus pumilus SG2 using a combination of UV irradiation and nitrous acid treatment. Following mutagenesis and screening on chitin agar and subsequent formation of halos, the mutated strains were examined for degradation of chitin under different conditions. A mutant designated AV2-9 was selected owing to its higher chitinase activity. To search for possible mutations in the whole operon including ChiS and ChiL, the entire chitinase operon, including the intergenic region, promoter, and two areas corresponding to the ChiS and ChiL ORF, was suquenced. Nucleotide sequence analysis of the complete chitinase operon from the SG2 and AV2-9 strains showed the presence of a mutation in the catalytic domain (GH18) of chitinase (ChiL). The results demonstrated that a single base change had occurred in the ChiL sequence in AV2-9. The wild-type chitinase, ChiL, and the mutant (designated ChiLm) were cloned, expressed, and purified in E. coli. Both enzymes showed similar profiles of activity at different ranges of pH, NaCl concentration, and temperature, but the mutant enzyme showed approximately 30% higher catalytic activity under all the conditions tested. The results obtained in this study showed that the thermal stability of chitinase increased in the mutant strain. Bioinformatics analysis was performed to predict changes in the stability of proteins caused by mutation.

• Journal of Microbiology and Biotechnology
• /
• 제14권2호
• /
• pp.302-311
• /
• 2004

Comamonas testosteroni (formerly Pseudomonas sp.) NCIMB 10643 can grow on biphenyl and alkylbenzenes $(C_2-C_7)$ via 3-substituted catechols. Thus, to identify the genes encoding the degradation, transposon-mutagenesis was carried out using pAG408, a promoter-probe mini-transposon with a green fluorescent protein (GFP), as a reporter. A mutant, NT-1, which was unable to grow on alkylbenzenes and biphenyl, accumulated catechols and exhibited an enhanced expression of GFP upon exposure to these substrates, indicating that the gfp had been inserted in a gene encoding a broad substrate range catechol 2,3-dioxygenase. The genes (2,826 bp) flanking the gfp cloned from an SphI-digested fragment contained three complete open reading frames that were designated bphCDorfl. The deduced amino acid sequences of bphCDorfl were identical to 2,3-dihydroxybiphenyl 1,2-dioxygenase (BphC), 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase (BphD), and OrfI, respectively, that are all involved in the degradation of biphenyl/4-chlorobiphenyl (bph) by Ralstonia oxalatica A5. The deduced amino acid sequence of the orfl revealed a similarity to those of outer membrane proteins belonging to the OmpW family. The introduction of the bphCDorfl genes enabled the NT-l mutant to grow on aromatic hydrocarbons. In addition, PCR analysis indicated that the DNA sequence and gene organization of the bph operon were closely related to those in the bph operon from Tn4371 identified in strain A5. Furthermore, strain A5 was also able to grow on a similar set of alkylbenzenes as strain NCIMB 10643, demonstrating that, among the identified aromatic hydrocarbon degradation pathways, the bph degradation pathway related to Tn4371 was the most versatile in catabolizing a variety of aromatic hydrocarbons of mono- and bicyclic benzenes.

• Journal of Microbiology
• /
• 제44권2호
• /
• pp.192-199
• /
• 2006

Pseudomonas putida KL47 is a natural isolate that assimilates benzene, 1-alkylbenzene $(C_1-C_4)$, biphenyl, p-cumate, and p-cymene. The genetic background of strain KL47 underlying the broad range of growth substrates was examined. It was found that the cym and cmt operons are constitutively expressed due to a lack of the cymR gene, and the tod operon is still inducible by toluene and biphenyl. The entire array of gene clusters responsible for the catabolism of toluene and p-cymene/p-cumate has been cloned in a cosmid vector, pLAFR3, and were named pEK6 and pEK27, respectively. The two inserts overlap one another and the nucleotide sequence (42,505 bp) comprising the cym, cmt, and tod operons and its flanking genes in KL47 are almost identical (>99 %) to those of P. putida F1. In the cloned DNA fragment, two genes with unknown functions, labeled cymZ and cmtR, were newly identified and show high sequence homology to dienelactone hydrolase and CymR proteins, respectively. The cmtR gene was identified in the place of the cmtI gene of previous annotation. Western blot analysis showed that, in strains F1 and KL47, the todT gene is not expressed during growth on Luria Bertani medium. In minimal basal salt medium, expression of the todT gene is inducible by toluene, but not by biphenyl in strain F1; however, it is constantly expressed in strain KL47, indicating that high levels of expression of the todST genes with one amino acid substitution in TodS might provide strain KL47 with a means of adaptation of the tod catabolic operon to various aromatic hydrocarbons.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2005년도 생물공학의 동향(XVI)
• /
• pp.554-554
• /
• 2005

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2002년도 총회 및 추계학술발표회
• /
• pp.45.2-46
• /
• 2002

• Journal of Microbiology
• /
• 제45권1호
• /
• pp.79-82
• /
• 2007

The 58 rRNA gene from Sphingobium chungbukense DJ77 was identified. The secondary structure of the 199-base-long RNA was proposed. The two-base-long D loop was the shortest among all of the known 5S rRNAs. The U19-U64 non-canonical pair in the helix II region was uniquely found in strain DJ77 among all of the sphingomonads.

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 2000년도 한국생물과학협회 학술발표대회
• /
• pp.255.2-255
• /
• 2000

No Abstract, See Full Text

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 2000년도 한국생물과학협회 학술발표대회
• /
• pp.257.2-257
• /
• 2000

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 2000년도 한국생물과학협회 학술발표대회
• /
• pp.258.1-258
• /
• 2000