中国生物工程杂志

Objective: To identify all the potential ORFs encoding secreted proteins in Escherichia coli UTI89 genome, and to preliminarily characterise the secreted proteins and the signal peptides. Methods: Entire 5211 ORFs were predicted by network softwares including SignalP3.0, TatP1.0, SecretomeP2.0, etc. The basic features of signal peptides and secreted proteins in prediction results were statistically analysed. The secreted proteins which have the same signal sequence were aligned by the programe Blast 2 Sequences. Results: 432 ORFs encoding Sec pathway secreted proteins, 19 ORFs encoding Tat pathway secreted proteins and 386 ORFs encoding non-classically secreted proteins exist in E. coli UTI89 genome. The mean length of signal peptides is 25.5 aa, and the mean length of secreted proteins is 282.8 aa. The top three frequent amino acids in signal peptides are L, A, S. Only two signal peptides have the same sequence, and the corresponding secreted proteins are highly homologous. Conclusions: 837 ORFs in E.coli UTI89 genome may encode secreted proteins. Lengths of most secreted proteins are less than 500 aa. Amino acids in signal peptides are relatively conservative, most of which are hydrophobic. Signal peptides diversify widely but the secreted proteins containing the same signal sequence are likely to be encoded by homologous genes.