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Immunity Protein (immunity + protein)
Selected AbstractsInactivation of colicin Y by intramembrane helix,helix interaction with its immunity proteinFEBS JOURNAL, Issue 21 2008David, majs The construction of hybrids between colicins U and Y and the mutagenesis of the colicin Y gene (cya) have revealed amino acid residues important for interactions between colicin Y and its cognate immunity protein (Cyi). Four such residues (I578, T582, Y586 and V590) were found in helices 8 and 9 of the colicin Y pore-forming domain. To verify the importance of these residues, the corresponding amino acids in the colicin B protein were mutated to the residues present in colicin Y. An Escherichia coli strain with cloned colicin Y immunity gene (cyi) inactivated this mutant, but not the wild-type colicin B. In addition, interacting amino acid pairs in Cya and Cyi were identified using a set of Cyi point mutant strains. These data are consistent with antiparallel helix,helix interactions between Cyi helix T3 and Cya helix 8 of the pore-forming domain as a molecular mechanism of colicin Y inactivation by its immunity protein. [source] Recognition of pore-forming colicin Y by its cognate immunity proteinFEMS MICROBIOLOGY LETTERS, Issue 1 2006David, majs Abstract Construction of hybrid immunity genes between colicin U (cui) and Y (cyi) immunity genes and site-directed mutagenesis of cyi were used to identify amino-acid residues of the colicin Y immunity protein (Cyi) involved in recognition of colicin Y. These amino-acid residues were localized close to the cytoplasmic site of the Cyi transmembrane helices T3 (S104, S107, F110, A112) and T4 (A159). Mutations in cui, which converted Cui sequence to Cyi sequence in positions 104, 107, 110, 112 and 159, resulted in an immunity gene that also conferred (besides immunity to colicin U) a high degree of immunity to colicin Y. [source] The biology of lantibiotics from the lacticin 481 group is coming of ageFEMS MICROBIOLOGY REVIEWS, Issue 2 2007Alain Dufour Abstract Lantibiotics are antimicrobial peptides from the bacteriocin family, secreted by Gram-positive bacteria. These peptides differ from other bacteriocins by the presence of (methyl)lanthionine residues, which result from enzymatic modification of precursor peptides encoded by structural genes. Several groups of lantibiotics have been distinguished, the largest of which is the lacticin 481 group. This group consists of at least 16 members, including lacticin 481, streptococcin A-FF22, mutacin II, nukacin ISK-1, and salivaricins. We present the first review devoted to this lantibiotic group, knowledge of which has increased significantly within the last few years. After updating the group composition and defining the common properties of these lantibiotics, we highlight the most recent developments. The latter concern: transcriptional regulation of the lantibiotic genes; understanding the biosynthetic machinery, in particular the ability to perform in vitro prepeptide maturation; characterization of a novel type of immunity protein; and broad application possibilities. This group differs in many aspects from the best known lantibiotic group (nisin group), but shares properties with less-studied groups such as the mersacidin, cytolysin and lactocin S groups. [source] Crystallization and preliminary X-ray data investigation of the bacterial enterocin A immunity protein at 1.65,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2003Bjørn Dalhus Crystals of the bacterial enterocin A immunity protein have been prepared by the hanging-drop vapour-diffusion technique at 293,K. The crystals diffract to better than 1.7,Å resolution and X-ray diffraction data to 1.65,Å have been collected at 110,K using synchrotron radiation. The enterocin A immunity protein crystals belong to the monoclinic crystal system, with unit-cell parameters a = 116.32, b = 42.35, c = 66.17,Å, , = 111.3°. The symmetry and systematic absences in the diffraction pattern are consistent with space group C2. The presence of two molecules in the asymmetric unit with a molecular weight of ,12.2,kDa gives a crystal volume per protein mass (VM) of ,3.1,Å3,Da,1 and a solvent content of ,60% by volume. [source] Crystallization of the cytotoxic domain of a ribosome-inactivating colicin in complex with its immunity proteinACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2000Stephen Carr The complex between the ribonuclease domain of the ribosome-inactivating colicin E3 and its protein inhibitor, the cognate immunity Im3, has been crystallized and preliminary X-ray characterization has been performed. Single crystals of the 1:1 complex were grown from hanging-drop vapour-diffusion experiments using 2-propanol as a precipitant. The space group is P3121 or P3221, with unit-cell parameters a = b = 93.7, c = 76.2,Å. When cryocooled, these crystals diffract to a resolution of 2.4,Å. A search for suitable conventional heavy-atom derivatives was unsuccessful and so Im3 mutants containing engineered cysteine or methionine residues have been produced for mercury soaks and selenomethionine-labelling experiments, respectively. [source] | |||||||||||||