Biochemistry

Some Like It Briny

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Science  16 Sep 2005:
Vol. 309, Issue 5742, pp. 1790
DOI: 10.1126/science.309.5742.1790c

Recent expeditions have exploited the power of metagenomics to prospect in harsh and hazardous environments for unusual and useful microbial molecules. Ferrer et al. have sampled a deep-sea hypersaline anoxic basin (DHAB) in the eastern Mediterranean, and then nurtured microbial growth by feeding with Arabian light crude. They have isolated a remarkable esterase, cataloged as O.16 (for more on DHAB microbes, see van der Wielen et al., Reports, p. 121, 7 January 2005). This enzyme reversibly adopts three quaternary structures: (i) a 104-kD monomer in standard buffer; (ii) a hetero-dimer of 21- and 85-kD chains upon disulfide reduction; and (iii) a 325-kD trimer under high pressure (20 MPa), high salt (3.5 M NaCl), and a reducing agent. In a fashion consistent with the ionic and anoxic conditions 3500 m below sea level, the activity of the trimer is maximal and about 700 times that of the monomer. Furthermore, in terms of its potential use in chemical synthesis, O.16 is stable in a variety of nonpolar and polar solvents. — GJC

Chem. Biol. 12, 895 (2005).

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