Journal of Microbiology

Journal Article

The putative sensor histidine kinase VadJ coordinates development and sterigmatocystin production in Aspergillus nidulans: Yanxia Zhao , Mi-Kyung Lee , Jieyin Lim , Heungyun Moon , Hee-Soo Park , Weifa Zheng , Jae-Hyuk Yu; J. Microbiol. 2021;59(8):746-752. Published online July 5, 2021; DOI: https://doi.org/10.1007/s12275-021-1055-2

14 View
0 Download
6 Citations

Abstract: The VosA-VelB heterocomplex governs expression of several genes associated with fungal development and secondary metabolism. In this study, we have investigated the functions of one of the VosA-VelB-activated developmental genes vadJ in development and production of the mycotoxin sterigmatocystin in the model fungus Aspergillus nidulans. The vadJ gene is predicted to encode a 957-amino acid length protein containing a highly conserved sensor histidine kinase domain. The deletion of vosA or velB resulted in decreased mRNA levels of vadJ throughout the life cycle, suggesting that VosA and VelB are necessary for proper expression of vadJ. Nullifying vadJ led to highly restricted colony growth, lowered formation of asexual spores, and about two-fold reduction in conidial viability. Conversely, the deletion of vadJ resulted in elevated production of sexual fruiting bodies and sterigmatocystin. These suggest that VadJ is necessary for proper coordination of asexual and sexual development, and sterigmatocystin production. In accordance with this idea, the deletion of vadJ led to elevated mRNA levels of the two key sexual developmental activators esdC and nsdD. In summary, the putative sensor histidine kinase VadJ represses sexual development and sterigmatocystin production, but activates asexual development in A. nidulans.

Characteristics of trypsin-like protease and metalloprotease associated with mycelium differentiation of streptomyces albidoflavus SMF301: Kang, Sung Gyun , Kim, In Seop , Jeong, Byung Cheol , Ryu, Jae Gon , Rho, Yong Taik , Lee, Kye Joon; J. Microbiol. 1995;33(4):307-314.

19 View
0 Download

Abstract: Trypsin like protease (TLP) and metalloprotease (MTP) were induced in associated with the mycelium differentiation in Streptomyces albidoflavus SMF301. TLP and MTP were purified and characterized from the culture. The molecular mass of TLP and MTP were estimated to be 32 kDa and 18 kDa, respectively. The molecular mass of TLP and MTP were estimated to be 32 kDa and 18 kDa, respectively. The optimum pH and temperature of TLP were 10 and 40℃. Those of MTP were 8 and 55 ℃. TLP was stable at alkaline pH (6-9) and unstable above 45℃ and MTP was stable at alkaline pH and unstable above 80℃. Km and Vmax values with benzoyl-arginyl p-nitroanilide of TLP were 139 uM, and 10 nmole of nitroanilide released per min per ㎍ protein, respectively. Km, and Vmax values with a synthetic substrate, leucine p-nitroanilide, or MTP were 58.9 uM, 3.47 nmol of nitroanilide released per min per/㎍ protein, respectively. TLP was inhibited competitively by leupeptin; the inhibition constant was 0.0031 uM. MTP was inhibited by EDTA, phenonthroline and bestatin.

Physiological importance of trypsin-like protease during morphological differentiation of streptomycetes: Kim, In Seop , Kang, Sung Gyun , Lee, Kye Joon; J. Microbiol. 1995;33(4):315-321.

11 View
0 Download

Abstract: The relationship between morphological differentiation and production of trypsin-like protease (TLP_ in streptomycetes was studied. All the Streptomyces spp. In this study produced TLP just before the onset of aerial mycelium formation. Addition of TLP inhibitor, TLCK, to the top surface of colonies inhibited aerial mycelium formation as well as TLP inhibitor, TLCK, to the top surface of colonies inhibited aerial mycelium formation as well as TLP activity. Addition of 2% glucose to the Bennett agar medium repressed both the aerial mycelium formation and TLP production in S. abuvaviensis, S. coelicolor A3(2), S exfoliatus, S. microflavus, S. roseus, s. lavendulae, and S. rochei. However the addition of glucose did not affect S. limosus, S. felleus, S. griseus, S. phaechromogenes, and S. rimosus. The glucose repression on aerial mycelium formation and production of TLP was relieved by the addition of glucose anti-metabolite (methyl α-glucopyranoside). Therefore, it was concluded that TLP production is coordinately regulated with morphological differentiation and TLP activity is essential for morphological differentiation in streptomycetes. The proposed role of TLP is that TLP participates in the degradation of substrate mycelium protein for providing nutrient for aerial mycelial growth.

Streptomyces griseus HH1, An A-factor Deficient Mutant, Produces Diminished Level of Trypsin and Increased Level of Metalloproteases: Jung-Mee Kim , Soon-Kwang Hong; J. Microbiol. 2000;38(3):160-168.

15 View
0 Download

Abstract: A-factor is a microbial hormone that can positively control cell differentiation leading to spore formation and secondary metabolite formation in Streptomyces griseus. To identify a protease that is deeply involved in the morphological and physiological differentiation of Streptomyces, the proteases produced by S. griseus IFO 13350 and its A-factor deficient mutant strain, S. griseus HH1, as well as S. griseus HH1 transformed with the afsA gene were studied. In general, S. griseus showed a higher degree of cell growth and protease activity in proportion to its ability to produce a higher amount of A-factor. In particular, the specific activity of the trypsin of S. griseus IFO 13350 was greatly enhanced more than twice compared with that of S. griseus HH1 in the later stage of growth. The specific activity of the metalloprotease of S. griseus HH1 was greatly enhanced more than twice compared with that of S. griseus IFO 13350, and this observation was reversed in the presence of thiostreptone. However, S. griseus HH1 transformed with the afsA gene showed a significantly decreased level of trypsin and metalloprotease activity compared with that of the HH1 strain. There was no significant difference between S. griseus IFO 13350 and HH1 strain in their chymotrypsin and thiol protease activity, yet the level of leu-aminopeptidase activity was 2 times higher in S. griseus HH1 than in strain IFO 13350. S. griseus HH1 harboring afsA showed a similar level of enzyme activity, however, all the three protease activities sharply increased and the thiol protease activity was critically increased at the end of the fermentation. When a serine protease inhibitor, pefabloc SC, and metalloprotease inhibitor, EDTA, were applied to strain IFO 13350 to examine the in vivo effects of the protease inhibitors on the morphological differentiation, the formation of aerial mycelium and spores was delayed by two or three days.

A Recombinant Human [alpha]_1-Antitrypsin Variant, M_malton, Undergoes a Spontaneous Conformational Conversion into a Latent Form: Chan-Hun Jung , Hana Im; J. Microbiol. 2003;41(4):335-339.

10 View
0 Download

Abstract: Many genetic variants of [alpha]_1-antitrypsin have been associated with early onset emphysema and liver cirrhosis. However, the detailed structural basis of pathogenic [alpha]_1-antitrypsin molecules is rarely known. Here we found that a recombinant M_malton variant (Phe52-deleted) lost inhibitory activity by spontaneous conformational conversion into a more stable, inactive form under physiological conditions. Biochemical and spectroscopic data suggested that the variant converts into a reactive center loop-inserted conformation, resembling the latent form of plasminogen activator inhibitor-1.

Streptomyces griseus Trypsin (SGT) Has Gelatinase Activity and Its Proteolytic Activity Is Enhanced by Manganese: Won-Jae Chi , Yoon-Hee Kim , Jong-Hee Kim , Dae-Kyung Kang , Sang-Soon Kang , Joo-Won Suh , Soon-Kwang Hong; J. Microbiol. 2003;41(4):289-294.

13 View
0 Download

Abstract: Gelatinase is a proteolytic enzyme that hydrolyzes gelatin. Gelatinolytic activity was detected from culture broths of Streptomyces griseus IFO13350 and HH1 by paper disc assays on 0.5% agar plates containing 1% gelatin. The concentrated extracellular protein from the S. griseus was analyzed by SDS polyacrylamide gel, and two proteins, with molecular weights of 30 and 28 kDa, respectively, were identified to have gelatinase activity by gelatin zymography. The protein with a molecular weight of 28 kDa was confirmed to be S. griseus trypsin (SGT). The effects of metal ions and metal chelators on the protease activity of the SGT were studied. Of the metal ions tested, only manganese was found to enhance the protease activity, 2.6 times, however, Co_2^+, Cu_2^+, and Zn_2^+, and metal chelators, such as EDTA and EGTA, inhibited the SGT activity. When the protease activity of the SGT was measured at various pHs, in the presence of 5 mM MnCl_2, its highest activity was at pH 11.0, whereas only 60% of the maximum activity was observed between pHs 4.0 and pH 6.0, and almost 80% activity between pHs 7.0 to pH 10.0. The protease activity was measured at various temperatures in the presence of 5 mM MnCl_2. The SGT was found to be stable up to 60℃ for 30 min, while only 16% of the enzyme activity remained at 60℃, and at 80℃ almost all the activity was lost. The optimal temperature for the protease activity was 50℃.

First
Prev
Page of 1
Next
Last

Search