Work

The FeMoco-deficient MoFe Protein Produced by a nifHDeletion Strain of Azotobacter vinelandii Shows Unusual P-cluster Features

Year: 2002

Type: article

Abstract: The His-tag MoFe protein expressed by the nifH deletion strain Azotobacter vinelandii DJ1165 (Delta(nifH) MoFe protein) was purified in large quantity. The alpha(2)beta(2) tetrameric Delta(nifH) MoFe protein is FeMoco-deficient based on metal analysis and the absence of the S = 3/2 EPR signal, which arises from the FeMo cofactor center in wild-type MoFe protein. The Delta(nifH) MoFe protein contains 18.6 mol Fe/mol and, upon reduction with dithionite, exhibits an unusually strong S = 1/2 EPR signal in the g approximately 2 region. The indigo disulfonate-oxidized Delta(nifH) MoFe protein does not show features of the P(2+) state of the P-cluster of the Delta(nifB) MoFe protein. The oxidized Delta(nifH) MoFe protein is able to form a specific complex with the Fe protein containing the [4Fe-4S](1+) cluster and facilitates the hydrolysis of MgATP within this complex. However, it is not able to accept electrons from the [4Fe-4S](1+) cluster of the Fe protein. Furthermore, the dithionite-reduced Delta(nifH) MoFe can be further reduced by Ti(III) citrate, which is quite unexpected. These unusual catalytic and spectroscopic properties might indicate the presence of a P-cluster precursor or a P-cluster trapped in an unusual conformation or oxidation state.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.m202061200

Authors: Markus W. Ribbe, Yilin Hu, Maolin Guo, Benedikt Schmid, Barbara K. Burgess

Institutions: University of California, Irvine, California Institute of Technology

Language: English

Topic: Metalloenzymes and iron-sulfur proteins

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,430

Funders: National Institutes of Health, National Institute of General Medical Sciences