This work has been supported by grants from Ministerio de Ciencia e Innovación (EUI2008-03631 to R.I.S.; BFU2009-07565/BMC, 70% funded by FEDER, and the programme CONSOLIDER-INGENIO 2010, CSD2009-00006, both to J.M.-D.), Spain. This material is based on work supported in part by the National Science Foundation under Grant 0742976 to L.J.S. Thanks are due to Dr. M. Bibb for S. coelicolor M510, M511 and M512 strains and to M.J. Jiménez Rufo for her excellent technical work
