Mass spectrometric identification of in vivo carbamylation of the amino terminus of Ectothiorhodospira mobilis high-potential iron-sulfur protein, isozyme 1.
The complete amino acid sequence of a novel high-potential iron-sulfur protein (HiPIP) isozyme 1 from the moderately halophilic phototrophic bacterium Ectothiorhodospira mobilis was determined by a combined approach of chemical and mass spectrometric sequencing techniques. By mass analysis of the apo- and holo-protein in the positive electrospray ionization mode using different electrospray solvents, the protein was found to be post-translationally modified by a moiety of 43 Da. Further analysis showed the nature and location of this modification to be a carbamyl group at the N-terminus of the HiPIP. This rare type of modification has previously been reported to occur in the water-soluble human lens alphaB-crystallin, class D beta-lactamases and some prokaryotic ureases, albeit at an internal lysine residue. In this paper, we discuss the mass spectrometric features of a carbamylated residue at the N-terminus of a peptide or a lysine side-chain during sequence analysis by collision-induced dissociation tandem mass spectrometry. Our data provide evidence for the first case of a prokaryotic carbamylated electron transport protein occurring in vivo.
Department of Biochemistry, Physiology and Microbiology, Laboratory for Protein Biochemistry and Protein Engineering, University of Ghent, B-9000 Ghent, Belgium.
G
G
Van Driessche
I
I
Vandenberghe
F
F
Jacquemotte
B
B
Devreese
J J
JJ
Van Beeumen
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002219:Carbamates / Q000737:chemistry; D020587:Ectothiorhodospira / Q000201:enzymology*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D013058:Mass Spectrometry; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D045322:Photosynthetic Reaction Center Complex Proteins
D001426:Bacterial Proteins; D002219:Carbamates; D007506:Iron-Sulfur Proteins; D010455:Peptides; D045322:Photosynthetic Reaction Center Complex Proteins; C007943:high potential iron-sulfur protein