George W. Ordal

Chemotactic repellents of Bacillus subtilis

A number of membrane-active agents, including uncouplers of oxidative phosphorylation, a permeant anion, and local anaesthetics, are repellents of Bacillus subtilis . These bacteria normally swim, but tumble occasionally. However, when given such a reagent, they tumble and then later resume the original frequency of swimming and tumbling (i.e they adapt). We suggest that repellents of B. subtilis act directly on the membrane to cause tumbling, rather than through orthodox chemoreceptors as for enteric bacteria, and further, that decrease of ≈, the high energy state of the membrane interpreted as electrochemical gradient of H + ions across the membrane (chemiosmotic hypothesis), causes tumbling and increase causes swimming.

Mutations in the right operator of bacteriophage lambda: Evidence for operator-promoter interpenetration

Abstract A set of virulent mutants of bacteriophage lambda have been selected from λv2 v3. The sites of mutation form two microclusters, both close to v3. Some of the mutants, selected for their ability to grow on a λ-lysogen, can also grow on a λdv carrier strain. They are called “supervirulent” and a mutation conferring super-virulence is called vs. The sites of mutation to vs lie between the presumed promoter mutants (x3, x7) and x13, implying that the operator and promoter interpenetrate each other. The relative affinities of λ repressor for binding, in vitro, to λv+, λv3, λvs326, and λv3 vs327 DNA were 1, 1 4 , 1 20 , and 1 4000 , respectively. We suggest that two separate mutations in the right operator are needed to confer virulence because promoter sites lie within the operator.

Inhibition of amino acid transport in Bacillus subtilis by uncouplers of oxidative phosphorylation.

Abstract The effect of three uncouplers of oxidative phosphorylation, trifluoromethoxycarbon-ylcyanidephenylhydrazone (FCCP), 3,3′,4′,5-tetrachlorosalicylanilide (TCSA), and pentachlorophenol (PCP), on transport of glycine and proline by Bacillus subtilis were examined. FCCP inhibited proline uptake uncompetitively, but glycine uptake competitively. TCSA inhibited proline uptake noncompetitively, but glycine uptake competitively. PCP inhibited proline uptake noncompetitively, but glycine uptake uncompetitively. The results indicate that these uncouplers inhibit amino acid transport by interacting at specific sites rather than by reducing any central supply of energy used to fuel metabolic processes.

Supervirulent Mutants and the Structure of Operator and Promoter

Bacteria carrying the plasmid λ dv (Matsubara and Kaiser, 1968) restrict the growth of λvir. However, it is possible to isolate mutants of λ that can grow on carriers of λ dv. The purpose of this report is to describe such mutants. The new locus of mutation is called vs , for supervirulence. Mutants having the genotype v 2 v 3 vs are supervirulent in the sense that they can grow on nonlysogenic bacteria, on λ lysogens, and on λ dv carriers. Experiments with these mutants suggest that the promoter may penetrate the operator in the right-hand operon of λ . Stocks of λv 2 v 3 contain mutants that form plaques on a lysogen at a frequency of about 10 −6 . One-tenth of these are supervirulent because they can also make plaques on a λ dv carrier. The remainder are ordinary virulent mutants, which cannot make plaques on λ dv carriers. This second class I shall denote vr , for restricted virulent. Jacob and Wollman’s (1954) v 1 is thus analogous to a vr mutation. Sixteen independent vs and nineteen independent vr mutants were isolated by plating on a lysogen separate stocks grown from single plaques of λv 2 v 3. MAPPING The 35 mutants were crossed with 2 reference mutants. λvs 326 and λvs 387. (All crosses were between λv 2 v 3 vs or λv 2 v 3 vr and λv 2 v 3 vs 326 or λv 2 v 3 vs 387.) Representative results are presented in Table 1. The supervirulent mutants fall into 2 classes: mutants of class I recombine with λvs 387 but not with λvs 326; mutants of class II recombine with λvs 326 but not with λvs 387. All of the λvr mutants belong to class...

Mutations in the right operator of bacteriophage lambda: Physiological effects☆

Abstract The right operator in bacteriophage lambda vs326 has one-twentieth the in vitro binding affinity for repressor as λv + ; for comparison λv3 has one-quarter the affinity of λv + . In vivo , both mutants constitutively express genes in the right operon. Both λv3 and λvs326 express gene O constitutively because they complement λimm434 O am − in a λ lysogen, vs , more efficiently than v3 . The v3 allele in cis (but not in trans ) to vs326 gives significantly greater phage yields in a λ lysogen than λvs326 alone, cro gene function, measured by arrest of exonuclease synthesis, suggested the following series of increasing degree of conatitutivity: v3, vs326, v3 vs326. λv2 vs326 forms plaques on lysogens that carry λ c I857, but λv2 v3 does not. These results indicate that vs326 , like v3 , is an operator constitutive mutation but stronger in its effects. These mutants exemplify a uniform correlation between relative weakness of repressor binding and degree of constitutive gene expression.

Association of Chemotaxis with Reduction of Cytochrome b in Bacillus subtilis

Addition of chemotactic attractant to Bacillus subtilis brought about a transient increase of absorption at 557 nm, compared with absorption at either 543 or 575.5 nm. The increase was tentatively attributed to reduction of cytochrome b. This reduction was linked to the ability of attractants (and certain other reagents) to make all bacteria in a population swim smoothly, rather than sometimes swimming and sometimes tumbling as they normally do. It is thought to signify a higher energy requirement for swimming since, in tumbling, flagella may tangle and jam, resulting in periods of no energy loss. Cations were required for motility; the function of the cations was probably not to energize motility, since protons alone could do that, but rather to reduce the surface potential of cells and, thus, avoid excess local acidity.