(a) The MccE492 gene cluster: mceA, 312 bp; mceB, 288 bp; mceC, 1113 bp; mceD, 1245 bp; mceE, 345 bp; mceF, 540 bp; mceG, 2097 bp; mceH, 1242 bp; mceI, 492 bp; mceJ, 1575 bp (ref. 1). (b) Amino acid sequences for the serine-rich C-termini of MccE492, MccH47, MccI47 and MccM. The sequence of the C-terminus of MccE492 was determined experimentally. MccH47, MccI47 and MccM have not been isolated and their C-terminal sequences were deduced from the respective genes.