lmost ubiquitous in the living species but highly diverse in structure and biological activity, host defence peptides interact with negatively charged cell mem branes, lead to microbe killing and modulate both the innate and inducible antimicrobial responses in mam mals. Four groups of AMP are known in mussels, defensins, selleck catalog mytilins myticins and mytimycins. The cationic and amphipatic structure of the mature peptides is stabilized by 4 intrachain disulphide bonds according to a unifying tridimensional motif. Mytibase includes the full length precursor sequences of all the mussel AMP with some new var iants, they are reported as mature peptide sequences in Figure 1. Myticins are subdivided in A, B and the polymorphic type C. Searching tBLASTn similarities to prototype sequences, we identified in Mytibase many precursors of myticin C, myticin A and myticin B.
Robust non synonymous SNPs analysis allowed us to split the sequence cluster of myticin A into 5 subgroups named A, A2, A3, A4 and A5, confirmed by 23, 38, 2, 21 and 4 sequence traces of high quality, respectively. Mytilin precursors are more heterogeneous in length ranging between 97 and 105 residues, and can be easily differentiated from the myticin precursors due to a dif ferent cysteine pattern. Similarly, we identified mytilin A, mytilin B, myti lin C, mytilin D. We could also extend the sequence of Mytilin G1 and we propose MGC00659 as Mytilin F, namely a new myti lin component. The defensin precursors identified in Mytibase are MGD1, MGD2b and three new sequences proposed as MGD3, MGD4, and MGD5.
Due to the presence of a stop codon just after the 8th conserved cystein, defensins MGD3 and MGD4 are shorter than the others whereas MGD5 is the longest with 97 aminoacid residues. Only one Mytibase EST corre sponds to the mytimycin described in M. edulis and four other sequences grouped from 4, 4, 4 and 3 ESTs may be regarded as new mytimycin variants. Cilengitide Curiously, two of these ESTs display a long insertion in the 5 UTR and a signal peptide with maximal cleavage prob abilities between positions 18 24 from ATG. cDNAs normalization was essential to reveal the rare mytimycin ESTs whereas the other more abundant AMP sequences can be easily and mainly attributed to hemocyte libraries prepared from immunostimulated Italian and Spanish mussels, without evidence of preferential geographical distribution.
All mussel AMP and one hydramacin like transcript have been included in the Immunochip. Transcripts containing C1q and Tumour Necrosis selleck chemical Factor like domains The overlapping C1q and TNF like domains have probably evolved by diver gence from an ancient recognition molecule whose diversification could have started with urochordates and cephalocordates. The large family of proteins with a C1q domain support many biological processes, from complement activation, modulatory immune func tions, apoptotic cell clearance to coagulation, embryonic development and tissue homeostasis. In mammals, the 18 polypeptide cha
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