TY - JOUR
T1 - Protonophore-resistance and cytochrome expression in mutant strains of the facultative alkaliphile Bacillus firmus OF4
AU - Quirk, Philip G.
AU - Guffanti, Arthur A.
AU - Plass, Robert J.
AU - Clejan, Sanda
AU - Krulwich, Terry Ann
N1 - Funding Information:
This research was supported by grants from the Department of Energy (DE-FGO2-86ER13559) and the National Institute of General Medical Sciences (GM28454).
PY - 1991/6/17
Y1 - 1991/6/17
N2 - Two protonophore-resistant mutants, designated strains CC1 and CC2, of the facultative alkaliphile Bacillus firmus OF4 811M were isolated. The ability of carbonyl cyanide m-chlorophenylhydrazone (CCCP) to collapse the protonmotive force (Δ over(μ, -)H+) was unimpaired in both mutants. Both resistant strains possessed elevated respiratory rates when grown at pH 7.5, in either the presence or absence of CCCP. Membrane cytochromes were also elevated: cytochrome o in particular in strain CC1, and cytochromes aa3, b, c and o in strain CC2. Strain CC2 also maintained a higher Δ over(μ, -)H+ than the others when grown in the absence of CCCP. When grown in the presence of low concentrations of CCCP, strains CC1 and CC2 both maintained higher values of Δ over(μ, -)H+ than the wild-type parent and correspondingly higher capacities for ATP synthesis. In large-scale batch culture at pH 10.5, both mutant strains grew more slowly than the parent and contained significantly reduced levels of cytochrome o. Cells of strain CC1 also displayed a markedly altered membrane lipid composition when grown at pH 10.5. Unlike previously characterized protonophore-resistant strains of B. subtilis and B. megaterium, neither B. firmus mutant possessed any ability above that of the parent strain to synthesize ATP at given suboptimal values of Δ over(μ, -)H+. Instead, both resistant alkaliphile strains maintained a higher Δ over(μ, -)H+ and a correspondingly higher ΔGp than the parent strain when growing in sublethal concentrations of CCCP, apparently as a result of mutational changes affecting respiratory chain composition. Also of note in both the mutant and the wild-type strains was a marked elevation in the level of one of the multiple terminal oxidases, an aa3-type cytochrome, during growth at pH 7.5 in the presence of CCCP or during growth at pH 10.5, i.e. two conditions that reduce the bulk Δ over(μ, -)H+.
AB - Two protonophore-resistant mutants, designated strains CC1 and CC2, of the facultative alkaliphile Bacillus firmus OF4 811M were isolated. The ability of carbonyl cyanide m-chlorophenylhydrazone (CCCP) to collapse the protonmotive force (Δ over(μ, -)H+) was unimpaired in both mutants. Both resistant strains possessed elevated respiratory rates when grown at pH 7.5, in either the presence or absence of CCCP. Membrane cytochromes were also elevated: cytochrome o in particular in strain CC1, and cytochromes aa3, b, c and o in strain CC2. Strain CC2 also maintained a higher Δ over(μ, -)H+ than the others when grown in the absence of CCCP. When grown in the presence of low concentrations of CCCP, strains CC1 and CC2 both maintained higher values of Δ over(μ, -)H+ than the wild-type parent and correspondingly higher capacities for ATP synthesis. In large-scale batch culture at pH 10.5, both mutant strains grew more slowly than the parent and contained significantly reduced levels of cytochrome o. Cells of strain CC1 also displayed a markedly altered membrane lipid composition when grown at pH 10.5. Unlike previously characterized protonophore-resistant strains of B. subtilis and B. megaterium, neither B. firmus mutant possessed any ability above that of the parent strain to synthesize ATP at given suboptimal values of Δ over(μ, -)H+. Instead, both resistant alkaliphile strains maintained a higher Δ over(μ, -)H+ and a correspondingly higher ΔGp than the parent strain when growing in sublethal concentrations of CCCP, apparently as a result of mutational changes affecting respiratory chain composition. Also of note in both the mutant and the wild-type strains was a marked elevation in the level of one of the multiple terminal oxidases, an aa3-type cytochrome, during growth at pH 7.5 in the presence of CCCP or during growth at pH 10.5, i.e. two conditions that reduce the bulk Δ over(μ, -)H+.
KW - (B. firmus OF4)
KW - Alkaliphile
KW - Cytochrome regulation
KW - Membrane lipid
KW - Protonmotive force
KW - Terminal oxidase
KW - Uncoupler resistance
UR - http://www.scopus.com/inward/record.url?scp=0025847887&partnerID=8YFLogxK
U2 - 10.1016/S0005-2728(05)80229-4
DO - 10.1016/S0005-2728(05)80229-4
M3 - Article
C2 - 1646630
AN - SCOPUS:0025847887
SN - 0005-2728
VL - 1058
SP - 131
EP - 140
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 2
ER -