Search PubMed⌕ Search

Biomedical subjects

T Iino

Publications and source records attributed to T Iino.

At least 145 records · Page 8Linked to original sources
PubMed1981

Analysis of flagellar genes in Pseudomonas aeruginosa by use of Rfla plasmids and conjugations.

Over 300 flagellar mutants were isolated in Pseudomonas aeruginosa PAO. R-prime plasmids carrying segments of bacterial chromosome which can complement the mutant phenotypes were isolated by means of plasmid R68.45. Among the R-prime plasmids, pMT6 complemented 167 out of 307 mutants examined, and pMT19 complemented the remaining 140 mutants. We found no mutant which was complemented by both of these plasmids. Hence, the flagellar genes were divided into two clusters by these two plasmids, namely, region I on pMT19 and region II on pMT6. By FP5- and R68.45-mediated conjugation, these two regions were located on the P. aeruginosa PAO chromosome with an order of puuF--region I--region II--oru-325.

Chromosome Mapping↗
PubMed1981

Role of the flaR gene in flagellar hook formation in Salmonella spp.

Flagellar filaments were reconstituted by polymerization with exogenously supplied flagellin monomers at the tips of normal hooks on Salmonella cells which were missing the filaments because of mutations in either the flaL or flaU gene or the flagellin genes H1 and H2. Reconstitution did not occur at the tips of polyhooks of the flaR mutant cells. Thus, the absence of flagellar filaments in the flaR mutant cells was probably caused by the inability of the polyhooks to work as polymerization nuclei for flagellin. A Phf+ mutant which produced polyhooks with flagellar filaments was isolated from a flaR polyhook mutant. Genetic analysis of the Phf+ mutant showed that it carried an intracistronic suppressor mutation of the original flaR mutation. This result indicated that the flaR gene regulates hook length and initiates flagellin formation.

Bacterial Proteins↗
PubMed1980

High frequency mobilization of the chromosome of Escherichia coli by a mutant of plasmid RP4 temperature-sensitive for maintenance.

Two mutants of plasmid RP4 temperature-sensitive for maintenance were isolated and one of them (pTH 10) was extensively studied. Cells carrying pTH10 showed temperature-sensitive drug resistance from which we isolated a number of temperature-independent derivatives. Almost all of them were Hfrs donating chromosomal genes to recipient bidirectionally from different points of origin. The Hfrs may be formed in two steps: (1) the transposon (Tn 1) carried by pTH 10 translocates into the host chromosome, and (2) pTH 10 is integrated in the host chromosome by reciprocal recombination between the TN 1 s, one situated on pTH 10 and another on the host chromosome. That temperature-independent drug resistance selects for this type of derivative, was supported by the following observations: (1) Hfrs thus obtained were usually unstable and segregated at high frequency 'revertants' showing temperature-sensitive drug resistance when they were cultivated at 30 degrees C. (2) The 'revertants' cured of pTH 10 were still ampicillin resistant, indicating existence of Tn 1 inserted in the host chromosome. (3) Tn 1 insertions found in these derivatives mapped in the vicinity of points of origin of the original Hfrs. (4) When new Hfrs were constructed by: (a) transduction with Plkc on Tn 1 insertions found in derivatives of Hfrs, (b) introduction of pTH 10 into the transductants,and (c) isolation of clones of temperature-independent drug resistance from such pTH 10 carrying stains, they had similar characteristics to the original Hfrs from which Tn 1 insertions were derived. Possibilities for genetic manupulation using pTH 10 in a wide range of Gram-negative bacteria are discussed.

Chromosomes, Bacterial↗
PubMed1980

Inversions of specific DNA segments in flagellar phase variation of Salmonella and inversion systems of bacteriophages P1 and Mu.

Prophages P1 and Mu produces a trans-acting factor possessing the din+ activity which catalyzes the inversion of the specific DNA segment responsible for flagellar phase variation of Salmonella, din mutants were isolated from PICMclr100 phage by selecting phages that did not suppress the yh2 mutation of Salmonella in prophage state. No inversion loop structure was detected among DNA forms arising after denaturation and rehybridization of DNAs extracted from the din mutants. The DNA fragment containing C region of P1 was cloned on a plasmid vector, pCR1. The resulting hybrid plasmid, pKK2, was shown to possess the din+ activity: the vh2 mutant of Salmonella harboring the plasmid changed the flagellar phase. From analysis of the plasmid by use of BamHI and Bgl II, the din gene specifying the din+ activity was located near or within the C region of P1. It is highly plausible that the din gene of P1 was also involved in the inversion of the C region. Similarly, the DNA fragment containing the G and beta segments of Mu was cloned on pCR1. The resulting hybrid plasmid, pII101, also possessed the din+ activity.

Bacterial Proteins↗
PubMed1980

Definition of additional flagellar genes in Escherichia coli K12.

Twenty-nine flagellar genes in Escherichia coli K12 have previously been assigned to three regions of the genome. Flagellar region I is located between pyrC and ptsG, region II between aroD and uvrC, and region III between uvrC and his. In this study, flagellar mutants in Escherichia coli K12 were obtained by selection for resistance to the flagellotropic phage, chi. They were analyzed in complementation tests using P1 phage-mediated transduction. In addition to the fla genes already described, eight more flagellar genes were identified. This analysis defined six more fla genes in region I (flaU, etc.), one more in region II (flbB) and one more in region III (flbC). Region I was shown to include at least 12 fla cistrons. Complementation analysis with polar Mu phage-induced Fla- mutants and with lambda fla phage defined four transcriptional units in region I. These were: flaU, flbA-flaW-flaV-flaK-flaX-flaL-flaY-flaM, flaZ and flaS- flaT, with transcription proceeding from left to right. The flB gene was found to be part of an operon: flB-flaI in region II. In region III, a previously unidentified gene flbC was located between hag and flaN.

Chromosome Mapping↗
PubMed1980

Isolation and characterization of multiflagellate mutants of Pseudomonas aeruginosa.

Multitrichously polar flagellated mutants were isolated from a monotrichously flagellated strain of Pseudomonas aeruginosa. The ability of the mutant cells to swarm in semisolid media at given gel strengths was increased by the multiflagellation. Observations of the mutant cells by electron microscopy revealed that the number of flagella produced per cell cycle was increased. F116 phage-mediated transduction showed that the multiflagellation occurred by a single mutation and that the mutation sites were linked to a fla cluster of this organism.

Cell Cycle↗
PubMed1979

Regulation of expression of the flagellin gene (hag) in Escherichia coli K-12: analysis of hag-lac gene fusions.

Previous studies have defined 28 genes necessary for the synthesis of the flagellar apparatus of Escherichia coli K-12. This study analyzed the influence of the flagellar genes on the expression of the hag gene (structural gene for flagellin). To this end, a hag::Mu d(Apr lac) mutant which had the lac genes fused to the promoter of the hag gene was constructed. This allowed the measurement of hag gene expression by detection of beta-galactosidase activity. The following observations were made. (i) The hag gene was expressed constitutively in Fla+ cells. (ii) hag gene expression was positively regulated by flaA, FLAB, flaC, flaD, flaE, flaG, flaH, flaI, flaK, flaL, flaM, flaN, flaO, flaP, flaQ, flaR, flaV, flaW, flaX, flaY, flaZ, flbA, and flbB genes.hag-lac expression was not observed in strains with these fla mutations. (iii) The hag gene was expressed in mutants with flaS, flaT, flaU, and flbC defects. Therefore, these genes were not involved in regulation of hag gene transcription.

Bacterial Proteins↗
PubMed1979

Role of gene flaFV on flagellar hook formation in Salmonella typhimurium.

Nine temperature-sensitive nonflagellate mutants defective in flaFV were isolated from a strain of Salmonella typhimurium. Among them three mutants were found to produce flagella with abnormally shaped (either straight or irregularly curved) hooks at the permissive temperature. Two mutations that rendered hooks straight were located in one of the eight segments of flaFV defined by deletion mapping. The mutation that rendered hooks irregularly curved was located in a different segment. An flaR mutation was introduced into the latter mutant. At the permissive temperature, the resulting double mutant produced polyhooks whose wavelength and amplitude were both exceedingly reduced. These polyhook structures were more thermolabile than those of the flaFV+ strain. Hook protein of the former strain was shown to have a slightly positive electric charge compared with that of the latter. From these results and other available information, it is inferred that flaFV is the structural gene for the hook protein in Salmonella.

Bacterial Proteins↗
PubMed1978

Incomplete flagellar structures in nonflagellate mutants of Salmonella typhimurium.

Incomplete flagellar structures were detected in osmotically shocked cells or membrane-associated fraction of many nonflagellate mutants of Salmonella typhimurium by electron microscopy. The predominant types of these structures in the mutants were cistron specific. The incomplete basal bodies were detected in flaFI, flaFIV, flaFVIII, and flaFIX mutants, the structure homologous to a basal body in flaFV mutants, the polyhook-basal body complex in flaR mutants, and the hook-basal body complex in flaL and flaU mutants. No structures homologous to flagellar bases or their parts were detected in the early-fla group nonflagellate mutants of flaAI, flaAII, flaAIII, flaB, flaC, flaD, flaE, flaFII, flaFIII, flaFVI, flaFVII, flaFX, flaK, and flaM. From these observations, a process of flagellar morphogenesis was postulated. The functions of the early-fla group are essential to the formation of S ring-M ring-rod complexes bound to the membrane. The completion of basal bodies requires succeeding functions of flaFI, flaFIV, flaFVIII, and flaFIX. Next, the formation of hooks attached to basal bodies proceeds by the function of flaFV and by flaR, which controls the hook length. Flagellar filaments appear at the tips of hooks because of the functions of flaL, flaU, and flagellin genes.

Flagella↗
PubMed1978

Isolation and characterization of motile Escherichia coli mutants resistant to bacteriophage chi.

Four mutants of Escherichia coli that are resistant to the flagellotropic phage chi, but are motile, were isolated. When they were observed in liquid culture bylight microscopy, one mutant exhibited circular movement and another tumbled at high frequency on the surface of a glass slide. The remaining two mutants moved normally. None of these mutants adsorbed the wild-type strain of chi. P1 transduction revealed that the mutation sites of these four mutants were more than 97% contransducible with a site in hag, the structural gene for flagellin. When flagellins of these mutants were chromatographed on a diethylaminoethyl-cellulose column, two eluted slower and one eluted slightly faster than the flagellin of the parental strain. The other flagellin eluted at the same position as that of the parent. Host range mutants of phage chi, which could infect these bacterial mutants, were isolated.

Adsorption↗
PubMed1977

Effects of galU mutation on flagellar formation in Escherichia coli.

Two mutants of Escherichia coli strictly deficient in uridine-diphosphoglucose pyrophosphorylase activity (galU) were found to have very small numbers of flagellar filaments and hooks. In these mutants, both the rate of flagellin (flagellar protein) synthesis and the amount of messenger ribonucleic acid specific for flagellin were considerably lower than in the parental strains. Motile revertants from the galU mutants were isolated and were found to carry a suppressor mutation, which was mapped in the flaH cistron. These strains formed swarms under conditions of catabolite repression; their intracellular concentration of cyclic adenosine 5'-monophosphate was the same as that in the parental strains. These results suggest that the outer membrane affects flagellar formation through the flaH gene product.

Escherichia coli↗
PubMed1977

Phototaxis and membrane potential in the photosynthetic bacterium Rhodospirillum rubrum.

Cells of the photosynthetic bacterium Rhodospirillum rubrum cultivated anaerobically in light show phototaxis. The behavior of individual cells in response to the phenomenon is reversal(s) of the swimming direction when the intensity of the light available to them abruptly decreases. The tactic response was inhibited by antimycin, an inhibitor of the photosynthetic electron transfer system. The inhibitory effect of antimycin was overcome by phenazine methosulfate. Motility of the cells was not impaired by antimycin under aerobic conditions. Valinomycin plus potassium also inhibited their phototactic response; however, valinomycin or potassium alone had no effect. A change in membrane potential of the cells was measured as an absorbance change of carotenoid. Changes in the membrane potential caused by "on-off" light were prevented by antimycin and by valinomycin plus potassium, but not by antimycin plus phenazine methosulfate nor valinomycin or potassium alone. The results indicated that the phototactic response of R. rubrum is mediated by a sudden change in electron flow in the photosynthetic electron transfer system, and that the membrane potential plays an important role in manifestation of the response.

Aerobiosis↗
PubMed1977

Ribonucleic acid polymerase mutant of Escherichia coli defective in flagella formation.

Escherichia coli K-12 mutants that are resistant to bacteriophage chi, defective in motility, and unable to grow at high temperature (42 degrees C) were isolated from among those selected for rifampin resistance at low temperature (30 degrees C) after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Genetic analysis of one such mutant indicated the presence of two mutations that probably affect the beta subunit of ribonucleic acid (RNA) polymerase: one (rif) causing rifampin resistance and the other (Ts-74) conferring resistance to phage chi (and loss of motility) and temperature sensitivity for growth. Observations with an electron microscope revealed that the number of flagella per mutant cell was significantly reduced, suggesting that the Ts-74 mutation somehow affected flagella formation at the permissive temperature. When a mutant culture was transferred from 30 to 42 degrees C, deoxyribonucleic acid synthesis accelerated normally, but RNA or protein synthesis was enhanced relatively little. The rate of synthesis of beta and beta' subunits of RNA polymerase was low even at 30 degrees C and was further reduced at 42 degrees C, in contrast to the parental wild-type strain. Expression of the lactose and other sugar fermentation operons, as well as lysogenization with phage lambda, occurred normally at 30 degrees C, suggesting that the mutation does not cause general shut-off of gene expression regulated by cyclic adenosine 3',5'-monophosphate.

Bacterial Proteins↗
PubMed1977

Isolation of specialized lambda transducing bacteriophages for flagellar genes (fla) of Escherichia coli K-12.

Specialized transducing lambda phages carrying the region III flagellar genes (fla) of Escherichia coli K-12 were isolated by a new method. A strain carrying both a cryptic lambda prophage near the his genes and a deletion of the attlambda gene was used as a starting strain. The lysogen of lambdacI857pga18-bio69 was isolated in which the prophage was integrated within the lambda cryptic genes by means of recombination with the residual lambda DNA. The strains with deletions starting within the prophage and ending in these fla genes were selected from among the heat-resistant survivors of the lysogen. They were then infected with heat-inducible and lysis-defective lambda phages and, thus, specialized transducing phage lines for hag and fla were obtained. High-frequency transfer lines of rare phages carrying the fla genes were isolated by inducing a strain carrying a heat-inducible lambda prophage near the his genes and selecting by transduction of a fla deletion strain. Preliminary characterization of these transducing phages is also reported.

Chromosome Mapping↗