The Q15H mutation enables Crh, a Bacillus subtilis HPr-like protein, to carry out some regulatory HPr functions, but does not make it an effective phosphocarrier for sugar transport.
Crh of Bacillus subtilis exhibits 45% sequence identity when compared to histidine-containing protein (HPr), a phosphocarrier protein of the phosphoenolpyruvate (PEP):sugar phosphotransferase system (PTS). Crh can be phosphorylated by ATP at the regulatory Ser-46 and similar to P-Ser-HPr, P-Ser-Crh plays a role in carbon-catabolite repression. The sequence around the phosphorylatable Ser-46 in Crh exhibits strong similarity to the corresponding sequence of HPr of Gram-positive and a few Gram-negative bacteria. In contrast, the catalytic His-15, the site of PEP-dependent phosphorylation in HPr, is replaced with a glutamine in Crh. When Gln-15 was exchanged for a histidyl residue, in vitro PEP-dependent enzyme I-catalysed phosphorylation of the mutant Crh was observed. However, expression of the crhQ15H mutant allele did not restore growth of a ptsH deletion strain on the PTS sugars glucose, fructose or mannitol or on the non-PTS sugar glycerol. In contrast, Q15H mutant Crh could phosphorylate the transcriptional activator LevR as well as LevD, the enzyme IIA of the fructose-specific lev-PTS, which together with enzyme I, HPr and LevE forms the phosphorylation cascade regulating induction of the lev operon via LevR. As a consequence, the constitutive expression from the lev promoter observed in a (delta)ptsH strain became inducible with fructose when the crhQ15H allele was expressed in this strain.
Martin-Verstraete
Isabelle
I
Unité de Biochimie Microbienne, CNRS URA 1300, Institut Pasteur,F-75724 Paris, France1.
Galinier
Anne
A
Institut de Biologie et Chimie des Protéines, CNRS UPR 412, F-69367 Lyon Cedex 07, France2.
Darbon
Emmanuelle
E
Laboratoire de Génétique des Microorganismes, INRA-CNRS URA 1925,F-78850 Thiverval-Grignon, France3.
Quentin
Yves
Y
Laboratoire de Chimie Bactérienne, CNRS UPR 9043, F-13009 Marseille, France4.
Kilhoffer
Marie-Claude
MC
Laboratoire de Biophysique, URA 491, Université Louis Pasteur,F-67401 Illkirch Cedex, France5.
Charrier
Véronique
V
Institut de Biologie et Chimie des Protéines, CNRS UPR 412, F-69367 Lyon Cedex 07, France2.
Haiech
Jacques
J
Laboratoire de Biophysique, URA 491, Université Louis Pasteur,F-67401 Illkirch Cedex, France5.
Rapoport
Georges
G
Unité de Biochimie Microbienne, CNRS URA 1300, Institut Pasteur,F-75724 Paris, France1.
Deutscher
Josef
J
Laboratoire de Génétique des Microorganismes, INRA-CNRS URA 1925,F-78850 Thiverval-Grignon, France3.
D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002241:Carbohydrates; D003470:Culture Media / Q000737:chemistry; D005990:Glycerol; D008969:Molecular Sequence Data; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D016415:Sequence Alignment
D001426:Bacterial Proteins; D002241:Carbohydrates; C118042:Crh protein, Bacillus subtilis; D003470:Culture Media; D010750:Phosphoproteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; D005990:Glycerol