测定了Escherichia coli P90CF[rec A ara △(lac pro B)F′ lac l, pro A^+ proB^+]及其依赖链霉素突变体(Str^D A)、抗链霉素突变体(Str^R A)和回复突变体的β-半乳糖苷酶活性。发现Str^D A的酶活性大大低于野生型的酶活性,而Str^R A...测定了Escherichia coli P90CF[rec A ara △(lac pro B)F′ lac l, pro A^+ proB^+]及其依赖链霉素突变体(Str^D A)、抗链霉素突变体(Str^R A)和回复突变体的β-半乳糖苷酶活性。发现Str^D A的酶活性大大低于野生型的酶活性,而Str^R A的酶活性与野生型的接近。不同的回复突变体,酶活性差别很大,最高的与野生型的接近,大多数介于野生型与Str^D A之间,少数低于Str^D A。测定了E. coli A19及其衍生株的β-半乳糖苷酶活性,并与其λcI857成斑率相比较。在VT977(S8+S3+S18+L6+L24+L27)和VT567(S8+L27)中,它们的成斑率分别是野生型的6.02倍和3.56倍,而β-半乳糖苷酶活性只有野生型的19.23％和28.02％。相反,VT711(S8+S4+L6+L24)的成斑率只是野生型的6×10^(-7),而β-半乳糖苷酶活性仍达野生型的33.20％。展开更多
In ribosomal protein S12 mutant or L24 mutant the expression of λΝ gene was depressed at translational level. To study its mechanism the λΝ gene region of λΝ lacZ gene fusion was trimmed from its 5′ end to 3′ ...In ribosomal protein S12 mutant or L24 mutant the expression of λΝ gene was depressed at translational level. To study its mechanism the λΝ gene region of λΝ lacZ gene fusion was trimmed from its 5′ end to 3′ end with DNA exonuclease III (DNA exoIII) in order to alter the TIR (translational initiation region) and the coding region of λΝ gene. After DNA sequencing 23 species of different λΝ lacZ fused genes were obtained. The β galactosidase activities of these deletants in ribosomal protein mutant were compared with that in wild type strain. The result indicated that (i) S12 mutant could affect 30S subunit’s binding to the TIR of λΝ gene messenger and cause the difficulty in forming 30S initiation complex and then decrease the efficiency of translational initiation; (ii) in S12 mutant the coding region of λΝ gene also affected the expression of λΝ gene; (iii) in L24 mutant the inhibition of λΝ gene expression was not related to translational initiation and the 5′ end of the coding region of λN gene, but related to the 3′ end of λΝ gene.展开更多
Ribosomal protein L24 is one of the two assembly-initiator proteins. L24 isessential for the early steps of the assembly of the E.coli 50S ribosomal subunit.The mutants harboring a mutated or lacked L24 protein had a ...Ribosomal protein L24 is one of the two assembly-initiator proteins. L24 isessential for the early steps of the assembly of the E.coli 50S ribosomal subunit.The mutants harboring a mutated or lacked L24 protein had a severe reduction ingrowth rate and deficiency in the amount of the large ribosomal subunit as well as atemperature-sensitive phenotype.We reported that in an L24 mutant T83(rplX),展开更多
Previous results in this laboratory indicated that in ribosomal protein S12 strepto-mycin-dependent mutants of Bacillus subtilis, the burst size of bacteriophage φ105 was decreased, and the protein synthesis was inhi...Previous results in this laboratory indicated that in ribosomal protein S12 strepto-mycin-dependent mutants of Bacillus subtilis, the burst size of bacteriophage φ105 was decreased, and the protein synthesis was inhibited, while the DNA and展开更多
Since Jacob and Monod proposed the operon model, a great quantity of data on the transcriptional control of gene expression have been accumulated. On the contrary, evidence for the translational control is relatively ...Since Jacob and Monod proposed the operon model, a great quantity of data on the transcriptional control of gene expression have been accumulated. On the contrary, evidence for the translational control is relatively less. Examples of this type of regulation include the expression of RNA phage genes and that of ribosomal protein genes展开更多
Pingyangmycin is an antitumor antibiotics developed jointly by the scientists of the Institute of Antibiotics, the Chinese Academy of Medical Sciences and North China Pharmaceutical Factory from Streptomyces verticill...Pingyangmycin is an antitumor antibiotics developed jointly by the scientists of the Institute of Antibiotics, the Chinese Academy of Medical Sciences and North China Pharmaceutical Factory from Streptomyces verticillus var. Pingyangensis. It is markedly effective against squamous cell carcinoma of the head, neck and the cervix and fairly effective against mammary, nasopharyngeal and esophageal carcinoma. Chemically it is A5 component of bleomycin. Bleomycin obtained from commercial展开更多
Ⅰ. INTRODUCTIONAll protein syntheses are carried out on ribosomes, therefore the ribosomes are extremely important to biological activities. So far the composition of the ribosomal structure including three kinds of ...Ⅰ. INTRODUCTIONAll protein syntheses are carried out on ribosomes, therefore the ribosomes are extremely important to biological activities. So far the composition of the ribosomal structure including three kinds of rRNAs and over filly ribosomal proteins has been elucidated in detail. But the exact functions of the ribosomal proteins remain almost totally unknown.展开更多
文摘In ribosomal protein S12 mutant or L24 mutant the expression of λΝ gene was depressed at translational level. To study its mechanism the λΝ gene region of λΝ lacZ gene fusion was trimmed from its 5′ end to 3′ end with DNA exonuclease III (DNA exoIII) in order to alter the TIR (translational initiation region) and the coding region of λΝ gene. After DNA sequencing 23 species of different λΝ lacZ fused genes were obtained. The β galactosidase activities of these deletants in ribosomal protein mutant were compared with that in wild type strain. The result indicated that (i) S12 mutant could affect 30S subunit’s binding to the TIR of λΝ gene messenger and cause the difficulty in forming 30S initiation complex and then decrease the efficiency of translational initiation; (ii) in S12 mutant the coding region of λΝ gene also affected the expression of λΝ gene; (iii) in L24 mutant the inhibition of λΝ gene expression was not related to translational initiation and the 5′ end of the coding region of λN gene, but related to the 3′ end of λΝ gene.
基金Project supported by the National Natural Science Foundation of China and Chinese Academy of Sciences.
文摘Ribosomal protein L24 is one of the two assembly-initiator proteins. L24 isessential for the early steps of the assembly of the E.coli 50S ribosomal subunit.The mutants harboring a mutated or lacked L24 protein had a severe reduction ingrowth rate and deficiency in the amount of the large ribosomal subunit as well as atemperature-sensitive phenotype.We reported that in an L24 mutant T83(rplX),
文摘Previous results in this laboratory indicated that in ribosomal protein S12 strepto-mycin-dependent mutants of Bacillus subtilis, the burst size of bacteriophage φ105 was decreased, and the protein synthesis was inhibited, while the DNA and
文摘Since Jacob and Monod proposed the operon model, a great quantity of data on the transcriptional control of gene expression have been accumulated. On the contrary, evidence for the translational control is relatively less. Examples of this type of regulation include the expression of RNA phage genes and that of ribosomal protein genes
文摘Pingyangmycin is an antitumor antibiotics developed jointly by the scientists of the Institute of Antibiotics, the Chinese Academy of Medical Sciences and North China Pharmaceutical Factory from Streptomyces verticillus var. Pingyangensis. It is markedly effective against squamous cell carcinoma of the head, neck and the cervix and fairly effective against mammary, nasopharyngeal and esophageal carcinoma. Chemically it is A5 component of bleomycin. Bleomycin obtained from commercial
基金Project supported by the National Natural Science Foundation of China.
文摘Ⅰ. INTRODUCTIONAll protein syntheses are carried out on ribosomes, therefore the ribosomes are extremely important to biological activities. So far the composition of the ribosomal structure including three kinds of rRNAs and over filly ribosomal proteins has been elucidated in detail. But the exact functions of the ribosomal proteins remain almost totally unknown.
