Structural and functional characterisation of the cytochrome P450 enzyme CYP268A2 from Mycobacterium marinum.

Members of the cytochrome P450 monooxygenase family CYP268 are found across a broad range of Mycobacterium species including the pathogens Mycobacterium avium, M. colombiense, M. kansasii, and Mmarinum CYP268A2, from M. marinum, which is the first member of this family to be studied, was purified and characterised. CYP268A2 was found to bind a variety of substrates with high affinity, including branched and straight chain fatty acids (C10-C12), acetate esters, and aromatic compounds. The enzyme was also found to bind phenylimidazole inhibitors but not larger azoles, such as ketoconazole. The monooxygenase activity of CYP268A2 was efficiently reconstituted using heterologous electron transfer partner proteins. CYP268A2 hydroxylated geranyl acetate and trans-pseudoionone at a terminal methyl group to yield (2E,6E)-8-hydroxy-3,7-dimethylocta-2,6-dien-1-yl acetate and (3E,5E,9E)-11-hydroxy-6,10-dimethylundeca-3,5,9-trien-2-one, respectively. The X-ray crystal structure of CYP268A2 was solved to a resolution of 2.0 Šwith trans-pseudoionone bound in the active site. The overall structure was similar to that of the related phytanic acid monooxygenase CYP124A1 enzyme from Mycobacterium tuberculosis, which shares 41% sequence identity. The active site is predominantly hydrophobic, but includes the Ser99 and Gln209 residues which form hydrogen bonds with the terminal carbonyl group of the pseudoionone. The structure provided an explanation on why CYP268A2 shows a preference for shorter substrates over the longer chain fatty acids which bind to CYP124A1 and the selective nature of the catalysed monooxygenase activity.

Changes in dietary practices and social organization during the pivotal late iron age period in Norway (AD 550-1030): isotope analyses of Merovingian and Viking Age human remains.

Human remains representing 33 individuals buried along the coast in northern Norway were analyzed for diet composition using collagen stable carbon and nitrogen isotope analysis. Where possible, both teeth and bone were included to investigate whether there were dietary changes from childhood to adulthood. A general shift was documented from the Merovingian Age 550-800 AD to the Viking Age AD 800-1050 (VA), with a heavier reliance on marine diet in the VA. Dietary life history data show that 15 individuals changed their diets through life with 11 of these having consumed more marine foods in the later years of life. In combination with (87) Sr/(86) Sr data, it is argued that at least six individuals possibly originated from inland areas and then moved to the coastal region where they were eventually interred. The trend is considered in relation to the increasing expansion of the marine fishing industry at this time, and it is suggested that results from isotope analyses reflect the expanding production and export of stockfish in this region.