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Signalling Peptide (signalling + peptide)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Oligopeptide permease is required for expression of the Bacillus thuringiensis plcR regulon and for virulence

MOLECULAR MICROBIOLOGY, Issue 4 2001
Myriam Gominet
PlcR is a pleiotropic regulator of virulence factors in the insect pathogen Bacillus thuringiensis and in the opportunistic human pathogen Bacillus cereus. It activates the transcription of at least 15 genes encoding extracellular proteins, including phospholipases C, proteases and enterotoxins. Expression of the plcR gene is autoregulated and activated at the onset of stationary phase. Here, we used mini-Tn10 transposition to generate a library of B. thuringiensis mutants, with the goal of characterizing genes involved in the expression of the plcR gene. Three mutant strains were identified carrying distinct mini-Tn10 insertions. The mutations impaired plcR expression and caused a deficient haemolytic phenotype, similar to the phenotype of a B. thuringiensis strain in which the plcR gene had been disrupted. The insertion sites of the three mini-Tn10 transposons mapped in a five-gene operon encoding polypeptides homologous to the components of the oligopeptide permease (Opp) system of Bacillus subtilis, and with a similar structural organization. By analogy, the five B. thuringiensis genes were designated oppA, B, C, D and F. In vitro disruption of the B. thuringiensis oppB gene reproduced the effect of the mini-Tn10 insertions (i.e. the loss of haemolytic activity) and reduced the virulence of the strain against insects. These phenotypes are similar to those of a ,plcR mutant. Opp is required for the import of small peptides into the cell. Therefore, plcR expression might be activated at the onset of stationary phase by the uptake of a signalling peptide acting as a quorum-sensing effector. The opp mutations impaired the sporulation efficiency of B. thuringiensis when the cells were cultured in LB medium. Thus, Opp is on the pathway that ultimately regulates Spo0A phosphorylation, as is the case in B. subtilis. However, analysis of plcR expression in ,oppB, ,spo0A and ,oppB,spo0A mutants indicates that Opp is required for plcR expression via a Spo0A-independent mechanism. [source]

Differences in the expression of the ASIP gene are involved in the recessive black coat colour pattern in sheep: evidence from the rare Xalda sheep breed

ANIMAL GENETICS, Issue 3 2008
L. J. Royo
Summary Here we have tested the hypothesis of association between different levels of agouti signalling peptide (ASIP) mRNA and the recessive black coat colour in the rare Xalda breed of sheep. To deal with this task, we first tested the possible action of both the dominant black extension allele (ED) and a 5-bp deletion (X99692:c.100_104del; Adel) in the ovine ASIP coding sequence on the black coat colour pattern in 188 Xalda individuals. The ED allele was not present in the sample and only 11 individuals were homozygous for the AdelASIP allele. All Xalda individuals carrying the Adel/Adel genotype were phenotypically black. However, most black-coated individuals (109 out of 120) were not homozygous for the 5-bp deletion, thus rejecting the Adel/Adel genotype as the sole cause of recessive black coat colour in sheep. Differences in expression of ASIP mRNA were assessed via RT-PCR in 14 black-coated and 10 white-coated Xalda individuals showing different ASIP genotypes (Awt/Awt, Awt/Adel and Adel/Adel). Levels of expression in black animals were significantly (P < 0.0001) lower than those assessed for white-coated individuals. However, the ASIP genotype did not influence the ASIP mRNA level of expression. The consistency of these findings with those recently reported in humans is discussed, and the need to isolate the promoter region of ovine ASIP to obtain further evidence for a role of ASIP in recessive black ovine pigmentation is pointed out. [source]

Plant signalling peptides: some recent developments

JOURNAL OF PEPTIDE SCIENCE, Issue 12 2007
Agata Bahyrycz
Abstract The subject of this review is plant signalling peptides, peptides of a new generation which regulate growth, differentiation, and other plant physiological functions. These peptides include systemin, the phytosulfokines (PSKs), ENOD40, CLAVATA3, Locus-S, POLARIS, IDA, and ROT4. On the basis of literature data and our own results we discuss their structure, biological properties, and structure/biological function relationship, especially for the more studied systemin and PSK-,. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source]