Summary
Maltose-negative mutations in the amylomaltase gene of Streptococcus pneumoniae were examined for the presence of nonsense mutations. Out of 28 single-site mutants tested, 3 were shown to be suppressible by an amber suppressor previously found by Gasc et al. (1979). In the presence of the suppressor these mutants manifested 10–30% of wild type amylomaltase activity. In addition to the amylomaltase governed by malM, and the maltosaccharide phosphorylase governed by malP (which maps to the side of malM distal to the regulatory gene, malR), a new maltose-inducible protein, governed by another gene, malX, was observed in gel electrophoretic patterns. The malX gene maps on the side of malM proximal to the malR gene. The approximate molecular weights of the amylomaltase, phosphorylase and malX polypeptides are 62,000, 87,000 and 50,000, respectively. There appear to be no polar effects of the nonsense mutations in the malM gene on synthesis of the gene products of either malP or malX. In a search for nonsense mutants at other loci, one was found in the end gene, which governs the major endonuclease, a membrane enzyme. None were detected among 5 mismatch-repair defective hex mutants analyzed.
Similar content being viewed by others
References
Davis B (1964) Disc electrophoresis — II Method and application to human serum proteins. Ann NY Acad Sci 121:404–427
Ephrussi-Taylor H, Sicard AM, Kamen R (1965) Genetic recombination in DNA induced transformation of pneumococcus. I. The problem of relative efficiency of transforming factors. Genetics 51:455–475
Gasc AM, Vacher J, Buckingham R, Sicard AM (1979) Characterization of an amber suppressor in pneumococcus. Mol Gen Genet 172:295–301
Lacks S (1966) Integration efficiency and genetic recombination in pneumococcal transformation. Genetics 53:207–235
Lacks S (1968) Genetic regulation of maltosaccharide utilization in pneumococcus. Genetics 60:685–706
Lacks S (1970) Mutants of Diplococcus pneumoniae that lack deoxyribonucleases and other activities possibly pertinent to genetic transformation. J Bacteriol 101:373–383
Lacks S, Greenberg B, Neuberger M (1975) Identification of a deoxyribonuclease implicated in the genetic transformation of Diplococcus pneumoniae. J Bacteriol 123:222–232
Lacks S, Hotchkiss RD (1960) Formation of amylomaltase after genetic transformation of pneumococcus. Biochem Biophys Acta 45:155–163
Rosenthal A, Lacks S (1977) Nuclease detection in SDS polyacrylamide gel electrophoresis. Anal Biochem 80:76–90
Stretton AOW, Brenner S (1965) Molecular consequences of the amber mutation and its suppression. J Mol Biol 12:456–465
Studier FW (1973) Analysis of bacteriophage T7 early RNAs and proteins on slab gels. J Mol Biol 79:237–248
Weber K, Osborn M (1969) The reliability of molecular weight determination by dodecyl sulfate polyacrylamide gel electrophoresis. J Biol Chem 244:4406–4412
Author information
Authors and Affiliations
Additional information
Communicated by L. Lerman
Rights and permissions
About this article
Cite this article
Weinrauch, Y., Lacks, S.A. Nonsense mutations in the amylomaltase gene and other loci of Streptococcus pneumoniae . Molec. Gen. Genet. 183, 7–12 (1981). https://doi.org/10.1007/BF00270130
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00270130