Phosphate ester hydrolysis is catalyzed by a bacterial transferrin: potential implications for in vivo iron transport mechanisms.
Two synergistic anions, p-nitrophenyl phosphate ester (NPP) and SO(4)(2-), were found to form new stable assemblies with Fe(3+) and a bacterial transferrin, FbpA (FbpA=ferric binding protein). Fe(3+)FbpA-SO(4) undergoes rapid anion exchange in the presence of NPP to form Fe(3+)FbpA-NPP. Formation of Fe(3+)FbpA-NPP was found to accelerate the rate of hydrolysis of the bound phosphate ester (k(hyd)=1.6 x 10(-6) s(-1) at 25 degrees C and pH 6.5) by >10(3) fold over the uncatalyzed reaction. These findings suggest a dual function for FbpA in vivo: transport of Fe(3+) across the periplasmic space to the inner membrane in certain gram-negative bacteria and hydrolysis of periplasmic polyphosphates.
Dhungana
Suraj
S
Department of Chemistry, Duke University, P.O. Box 90346, Durham, NC 27708-0346, USA.
Anderson
Damon S
DS
Mietzner
Timothy A
TA
Crumbliss
Alvin L
AL
D000838:Anions; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D007501:Iron / Q000737:chemistry; D010755:Organophosphates / Q000737:chemistry*; D013053:Spectrophotometry; D013431:Sulfates / Q000737:chemistry; D014168:Transferrin / Q000378:metabolism*
D000838:Anions; D002352:Carrier Proteins; D010755:Organophosphates; D013431:Sulfates; D014168:Transferrin; D007501:Iron