title: Defect in the formation of 70S ribosomes caused by lack of ribosomal protein L34 can be suppressed by magnesium.
abstract: To elucidate the biological functions of the ribosomal protein L34, which is encoded by the rpmH gene, the rpmH deletion mutant of Bacillus subtilis and two suppressor mutants were characterized. Although the ΔrpmH mutant exhibited a severe slow-growth phenotype, additional mutations in the yhdP or mgtE gene restored the growth rate of the ΔrpmH strain. Either the disruption of yhdP, which is thought to be involved in the efflux of Mg(2+), or overexpression of mgtE, which plays a major role in the import of Mg(2+), could suppress defects in both the formation of the 70S ribosome and growth caused by the absence of L34. Interestingly, the Mg(2+) content was lower in the ΔrpmH cells than in the wild type, and the Mg(2+) content in the ΔrpmH cells was restored by either the disruption of yhdP or overexpression of mgtE. In vitro experiments on subunit association demonstrated that 50S subunits that lacked L34 could form 70S ribosomes only at a high concentration of Mg(2+). These results showed that L34 is required for efficient 70S ribosome formation and that L34 function can be restored partially by Mg(2+). In addition, the Mg(2+) content was consistently lower in mutants that contained significantly reduced amounts of the 70S ribosome, such as the ΔrplA (L1) and ΔrplW (L23) strains and mutant strains with a reduced number of copies of the rrn operon. Thus, the results indicated that the cellular Mg(2+) content is influenced by the amount of 70S ribosomes.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Tokyo, Japan akanuma@kc.chuo-u.ac.jp.
authors.forename: Genki
authors.initials: G
authors.lastname: Akanuma
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Tokyo, Japan.
authors.forename: Ako
authors.initials: A
authors.lastname: Kobayashi
authors.affiliation: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Tokyo, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Tokyo, Japan.
authors.forename: Fujio
authors.initials: F
authors.lastname: Kawamura
authors.affiliation: Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Tokyo, Japan.
authors.forename: Yuh
authors.initials: Y
authors.lastname: Shiwa
authors.affiliation: Department of Bioscience, Tokyo University of Agriculture, Tokyo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Tokyo, Japan Department of Bioscience, Tokyo University of Agriculture, Tokyo, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshikawa
authors.affiliation: Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Tokyo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Hanai
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Tokyo, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Ishizuka
mesh_terms: D001412:Bacillus subtilis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D005816:Genetic Complementation Test; D008274:Magnesium / Q000378:metabolism*; D009154:Mutation; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D012269:Ribosomal Proteins; C041672:ribosomal protein L34; D008274:Magnesium