Environmental Science and Engineering Seminar
Nearly all bacteria require iron to grow, and thus iron is an object of competition among microbes. Microbes often produced siderophores - small molecules with high ferric ion affinity - to sequester and facilitate transport of Fe(III) into and within bacteria. In marine bacteria, which face an extreme paucity of iron in surface ocean water, distinct structural classes of siderophore have been identified. One example, highlighted through recent genome screening is a class of tris catechol siderophores defined by a combinatoric library of D- and L- amino acids (e.g., Lys, Arg, Orn) that are produced by marine and pathogenic microbes. While catechols (2,3 dihydroxy-phenylalanine, 2,3-DHBA and 3,4-DHBA) are important in siderophores for Fe(III) coordination, catechols also play an important role in surface adhesion in mussel foot proteins (mfps), which contain 3,4-dihydroxyphenylalanine (DOPA). The susceptibility of the catechol towards oxidation, crosslinking, metal coordination – particularly with Fe(III) – or mineral interaction depends on the nature of the catechol. In some mfps the catechol content is as high as 30 mol percent DOPA and matched by an equally high content of Lys or Arg. Some siderophores also have an equal ratio of catechol (2,3-DHBA) and cationic amine, such as Lys in cyclic trichrysobactin, Arg in trivanchrobactin and Orn in turnerbactin. We are interested in the biosynthesis, chemical biology and adhesive properties of these catechol siderophores and synthetic analogs.