Enzymatic synthesis of layered titanium phosphates at low temperature and neutral pH by cell-surface display of silicatein-alpha.
We introduce a novel method of inorganic synthesis using the catalytic and structure-directing properties of the demosponge enzyme silicatein-alpha. Recombinant silicatein-alpha was displayed at the surface of Escherichia coli cells by fusion to outer membrane protein A and used to biocatalytically direct the formation of layered and amorphous titanium phosphates from a small water-soluble precursor at near-neutral pH at 16 degrees C. Synthesis of titanium phosphates, with potential applications in catalysis and separation technology, previously has required prolonged reactions with phosphoric acid at elevated temperatures. Additionally, we use library screening to isolate a 15-mer with affinity toward the silicatein active site (Kd ca. 50 nM) and introduce this new approach to demonstrate the success of our display strategy. Considering our previous findings with native silicatein filaments, we suggest that this scalable, efficient, cell-based system may have a broad utility for the synthesis of a range of structured metallophosphates and other inorganic materials.
Curnow
Paul
P
Institute for Collaborative Biotechnologies, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
Bessette
Paul H
PH
Kisailus
David
D
Murr
Meredith M
MM
Daugherty
Patrick S
PS
Morse
Daniel E
DE
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D002384:Catalysis; D002403:Cathepsins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D015335:Molecular Probes / Q000032:analysis; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014025:Titanium / Q000737:chemistry* / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D015335:Molecular Probes; D011993:Recombinant Fusion Proteins; C112571:silicatein alpha; C078167:OMPA outer membrane proteins; C036532:titanium phosphate; D014025:Titanium; D002403:Cathepsins