tailieunhanh - Báo cáo khoa học: Experimental proof for a signal peptidase I like activity in Mycoplasma pneumoniae, but absence of a gene encoding a conserved bacterial type I SPase

Although the annotation of the complete genome sequence ofMycoplasma pneumoniaedid not reveal a bacterial type I signal peptidase (SPase I) we showed experimentally that such an activity must exist in this bacterium, by determining the N-terminus of the N-terminal gene product P40 of MPN142, formerly called ORF6 gene. Combining mass spectrometry with a method for sulfonating specifically the free amino terminal group of proteins, the cleavage site for a typical signal peptide was located between amino acids 25 and 26 of the P40 precursor protein. . | iFEBS Journal Experimental proof for a signal peptidase I like activity in Mycoplasma pneumoniae but absence of a gene encoding a conserved bacterial type I SPase Ina Catrein Richard Herrmann Armin Bosserhoff and Thomas Ruppert Zentrum fur Molekulare Biologie Heidelberg Universitat Heidelberg Germany Keywords chemicalassisted fragmentation CAF mass spectrometry protein modification signal peptidase Correspondence T. Ruppert Zentrum fur Molekulare Biologie Heidelberg Universitat Heidelberg Im Neuenheimer Feld 282 69120 Heidelberg Germany Fax 49 6221 545891 Tel 49 6221 546895 E-mail Although the annotation of the complete genome sequence of Mycoplasma pneumoniae did not reveal a bacterial type I signal peptidase SPase I we showed experimentally that such an activity must exist in this bacterium by determining the N-terminus of the N-terminal gene product P40 of MPN142 formerly called ORF6 gene. Combining mass spectrometry with a method for sulfonating specifically the free amino terminal group of proteins the cleavage site for a typical signal peptide was located between amino acids 25 and 26 of the P40 precursor protein. The experimental results were in agreement with the cleavage site predicted by computational methods providing experimental confirmation for these theoretical analyses. Received 15 December 2004 revised 11 March 2005 accepted 7 April 2005 doi Mycoplasma pneumoniae is a human pathogenic bacterium 1 2 characterized by a small genome of 816 kbp 3 the lack of a bacterial cell wall and a parasitic lifestyle 4 . Some species of the genus mycoplasma . Mycoplasma genitalium Mycoplasma gallisepticum and Mycoplasma pneumoniae exhibit a flask-like shape which is believed to be formed and maintained by a cytoskeleton-like structure 5-10 . This flask-like shape is caused by the attachment organelle an asymmetric extension of the cell composed of an assembly of unique proteins 11 . M. pneumoniae