• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.250-255
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• 1994

Wild-type and four mutant R100 merR genes were cloned and the proteins overproduced under tac promoter control of pKK223-3. His118Ala, Cys117Ser, Cys126Ser, and wild-type MerR were successfully overproduced although amino-terminal 14 amino acids deletion mutant MerR was not successful. The amount of overproduced wild-type MerR protein as well as other mutant MerR was between 15%-20% of the total protein. The protein was able to be purified up to 95% homogeneity. Specific DNA-protein blotting experiments showed that the 95 bp operator containing DNA fragment could bind to Cys126Ser, His118Ala, and wild- type MerR, but not to Cys117Ser. These results were consistent with the previously reported complementation experiment results that His118Ala, Cys126Ser, and wild-type MerR could repress the mer operon but Cys117Ser could not.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2549-2552
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• 2011

In this study, the kinetic properties of wild-type and C117D mutant H. influenzae MurA (Hi MurA), which catalyzes the first reaction in the biosynthetic pathway of the cell wall, were characterized. Purified recombinant Hi MurA was active at pH values ranging from pH 5.5 to pH 10, and its $K_m$ (UNAG), $K_m$ (PEP), and $k_{cat}$ values were measured to be 31 ${\mu}M$, 24 ${\mu}M$, and 210 $min^{-1}$, respectively. Hi MurA activity was effectively inhibited by fosfomycin with an $IC_{50}$ value of 60 ${\mu}M$. Hi MurA contains a cysteine residue (C117) at the loop region near the PEP binding, whereas MurA from fosfomycin resistant Mycobaterium tuberculosis or Chlamydia trachomatis contain an aspartate residue instead of the cysteine at the corresponding site. Aspartate substitution of Cys117 in Hi MurA shifted its optimum pH from 7.8 to 6.0. In addition, the $K_m$ values for UNAG and PEP were increased to 160 ${\mu}M$ and 150 ${\mu}M$, respectively, and the $k_{cat}$ value was significantly reduced to 41 $min^{-1}$. Furthermore, the C117D mutant form of Hi MurA was not inhibited by 1 mM fosfomycin. These results indicate that the Cys117 of Hi MurA is the binding site of fosfomycin and plays an important role in the fast turnover of the catalytic reaction.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.245-249
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• 1994

An amino-terminal 14 amino acids deletion and three site-directed mutations were created to investigate the mechanism of induction and repression of MerR regulatory protein in R100 mer operon from gramnegative Shigella flexneri. The amino-terminal 14 amino acids deletion, Cysl17Ser, and Cys126Ser mutations abolished the inducibility of the mer operon and the Hisl18Ala mutation resulted in the reduction of inducibility (about 9.1 % remaining) in complementation experiment in the presence of $Hg^{2＋}$ at subtoxic level ($1\mu M$). The complementation experiment with $Hg^{2＋}$ absent showed that Hisl18Ala, Cys126Ser, and wild-type MerR could repress the operon but Cysl17Ser could not, and the amino-terminal deletion mutant could neither induce nor repress the R100 mer operon.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.117-122
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• 2019

Myxococcus stipitatus, a myxobacterium, forms spherical fruiting bodies with stems on edaphic substrates in enrichment cultures for isolation. However, an agar medium on which purely isolated strains of M. stipitatus form this type of fruiting bodies has not been known until now. In this study, since M. stipitatus DSM 14675 forms a hemispherical fruiting body-like structure on CYS agar medium, the effects of CYS medium components on fruiting body formation were investigated. Based on the results obtained, an agar medium on which M. stipitatus forms spherical fruiting bodies with stems was developed. Additionally, a liquid medium in which M. stipitatus grows in a dispersed manner was also formulated in this investigation.

• Applied Biological Chemistry
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• v.6
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• pp.107-117
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• 1965

(1) In order to study the specificity of Aspergillus soya protease to soybean protein, as well as the types of peptides formed during soybean-koji prerapation the amino acid sequence for the di & tripeptide and N-terminal amino acid residue and C-terminal amino acid residue were identified. As the results of the study, the following were obtained. Gly, Glu. Ala. Ser. Glu. Ser. Ala. Val (Cys, Glu, Ser, Ala, Arg, Try, Leu or Ileu) Asp. Phe (His, Arg, Cys, Asp, Ser, Ala, Leu or Ileu) Glu. Ala (Cys, Gly, Met) Glu. Ala (Asp, Glu,) Gly. Met (Asp, Glu, Ala, Tyr, Leu or Ileu, Lys,) Gly. Leu or Ileu (His, Asp, Glu, Gly, Ser, Lys, Thr, Phe,) Cys. Gly (Asp, Tyr,) Glu. Pro (Asp, Glu, Ser, Gly, Thr, Ala, Val, Leu or Ileu) Try. Ser (Gly, Glu, Arg, Ala, Met, Leu or Ileu,) Asp. Met (Asp, Glu, Ala, Try, Pro, Leu or Ileu,) His Thr (Ser, Gly, Tyr, Pro, Leu or Ileu,) Glu. Gly (Asp, Ala, Ser, Glu,) Leu or Ileu (2) It has revealed that Aspergillus soya protease has considerably wider range of specificity than that of chymotrypsin, pepsin and trypsin but not mold protease and Aspergillus saitoi protease. It can be said that Asp. soya protease split the bond adjacent to glutamic acid, aspartic acid, glycine, serine, alanine, cystine, tryptophan, histidine preferably acidic amino acid as C-terminal amino acid residue.

• Journal of Microbiology
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• v.44 no.5
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• pp.556-561
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• 2006

A differential display for the expression profiles of wild-type Cryphonectria parasitica and its virally-infected isogenic hypovirulent strain revealed several transcripts of interest, which evidenced significant matches with fungal genes of known function. Among which, we have further analyzed an amplified PCR product with significant sequence similarity to the known fungal stress-responsive thioredoxin gene from Neurospora crassa. The product of the cloned thioredoxin gene, CpTrx1, consists of 117 amino acids, with a predicted molecular mass of 13.0 kDa and a pI of 5.4. Sequence comparisons demonstrated that the deduced protein sequence of the CpTrx1 gene evidenced a high degree of homology to all known thioredoxins, with the highest degree of homology with trx1, a thioredoxin gene from Saccharomyces cerevisiae, and evidenced a preservation of the conserved hall markresidues (Trp-Cys-Gly-Pro-Cys) at the active site of thioredoxin. The E. coli-generated CpTRX1 manifested thioredoxin activity, according to the insulin reduction assay, which indicates that the cloned gene does indeed encode for the C. parasitica thioredoxin.

• Journal of Microbiology and Biotechnology
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• v.19 no.12
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• pp.1582-1589
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• 2009

Bacterial UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) catalyzes the transfer of enolpyruvate from phosphoenolpyruvate (PEP) to uridine diphospho-N-acetylglucosamine (UNAG), which is the first step of bacterial cell wall synthesis. We identified thimerosal, thiram, and ebselen as effective inhibitors of Haemophilus influenzae MurA by screening a chemical library that consisted of a wide range of bioactive compounds. When MurA was preincubated with these inhibitors, their 50% inhibitory concentrations ($IC_{50}s$) were found to range from 0.1 to $0.7\;{\mu}M$. In particular, thimerosal suppressed the growth of several different Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium at a concentration range of $1-2\;{\mu}g/ml$. These inhibitors covalently modified the cysteine residue near the active site of MurA. This modification changed the open conformation of MurA to a more closed configuration, which may have prevented the necessary conformational change from occurring during the enzyme reaction.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.3
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• pp.165-181
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• 1976

Fertilizer(N,P,K) demand for crop production in 1980, 1990 and 2000 was estimated according to the two proposed models, one of which is fertilizer use efficiency model expressed in $Fn=(Y/E){\cdot}(1-Cs)Eu$, where Fn:fertilizer demand, Y:Crop production estimated, E:nutrient efficiency, Cs:fraction of natural resource nutrient in plant, Eu:fertilizer use efficiency and the other fertilization efficiency model expressed in Fn=Y(1-Cys)/Fe, where Cys:fraction of yield without fertilizer, Fe:fertilization efficiency. Total crop uptake of nutrient and its noncycling portion were estimated as criteria for fertilizer demand and nutrient maintenance. Total crop uptake of N,P,K was 600,000 M/T in 1965 700,000 M/T in 1974 and estimated to 880,000 M/T in 1980, 1,170,000 M/T in 1990 and 1,410,000 M/T in 2000. Fertilizer demand appeares to be about 90% of total crop uptake according to fertilizer use efficiency model and about 87% according to fertilization efficiency model. The noncycling nutrient was about 29% of total crop uptake. Fertilizer demand was almost same to the uptake amount in nitrogen, 1.5 times of uptake in phosphorus and half of uptake in potassium. Varietal development, improvement of soil fertility and cultivation method and development of fertilizer forms appears to decrease fertilizer demand by increasing efficiency term in two models while environmental stress such as low temperature appears to give reverse effect resulting in higher fertilizer demand. Fertilizer consumption in 1974 seemed to be unreasonably high especially in nitrogen and phosphorus and thus the effective use of fertilizer appeared as an urgent problem considering that large fields are still remained in lower fertility.