02003nas a2200253   4500000000100000008004100001260004600042653001500088653002100103653001300124653002500137653001100162653001600173100001100189700001000200700002300210700002300233245010600256856007300362300001100435490000700446520128200453022001401735       2011                            d  c2011 MarbOxford University PressaOxford10aGene Order10aGenes, Bacterial10aGenomics10aMycobacterium leprae10aOperon10aPseudogenes1 aMuro E1 aMah N1 aMoreno-Hagelsieb G1 aAndrade-Navarro MA00aThe pseudogenes of Mycobacterium leprae reveal the functional relevance of gene order within operons.  uhttp://nar.oxfordjournals.org/content/39/5/1732.full-text-lowres.pdf  a1732-80 v393 a<p>Almost 50 years following the discovery of the prokaryotic operon, the functional relevance of gene order within operons remains unclear. In this work, we take advantage of the eroded genome of Mycobacterium leprae to add evidence supporting the notion that functionally less important genes have a tendency to be located at the end of its operons. M. leprae's genome includes 1133 pseudogenes and 1614 protein-coding genes and can be compared with the close genome of M. tuberculosis. Assuming M. leprae's pseudogenes to represent dispensable genes, we have studied the position of these pseudogenes in the operons of M. leprae and of their orthologs in M. tuberculosis. We observed that both tend to be located in the 3' (downstream) half of the operon (P-values of 0.03 and 0.18, respectively). Analysis of pseudogenes in all available prokaryotic genomes confirms this trend (P-value of 7.1 × 10(-7)). In a complementary analysis, we found a significant tendency for essential genes to be located at the 5' (upstream) half of the operon (P-value of 0.006). Our work provides an indication that, in prokarya, functionally less important genes have a tendency to be located at the end of operons, while more relevant genes tend to be located toward operon starts.</p>  a1362-4962