FlgM proteins from different bacteria exhibit different structural characteristics.
Intrinsically disordered proteins (IDPs) are a unique class of proteins that do not require a stable structure for function. The importance of IDPs in many biological processes has been established but there remain unanswered questions about their evolution and conservation of their disordered state within a protein family. Our group has been studying the structural similarities among orthologous FlgM proteins, a model class of IDPs. We have previously shown that the FlgM protein from the thermophile Aquifex aeolicus has more structure at A. aeolicus' physiological temperature (85°C) than is observed for the Salmonella typhimurium FlgM, suggesting that the disordered nature of FlgM varies among organisms and is not universally conserved. In this work, we extend these studies to the FlgM proteins from Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Bacillus subtilis. We demonstrate that the B. subtilis, E. coli, and S. typhimurium FlgMs exist in a premolten globule-like conformation, though the B. subtilis FlgM is in a more compacted conformation than the other two. The P. aeruginosa and P. mirabilis FlgM proteins exist in a currently unknown conformation that is not either coil-like or premolten globule-like. The P. aeruginosa FlgM appears to contain more weak intramolecular contacts given its more compacted state than the P. mirabilis FlgM. These results provide experimental evidence that members of the same protein family can exhibit different degrees of disorder, though understanding how different disordered states evolve in the same protein family will require more study.
Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, AZ 86011, USA.
Wai Kit
WK
Ma
Rachel
R
Hendrix
Claire
C
Stewart
Eric V
EV
Campbell
Mitchell
M
Lavarias
Kolyn
K
Morris
Shauna
S
Nichol
Matthew J
MJ
Gage
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D055550:Protein Stability; D011550:Pseudomonas aeruginosa / Q000737:chemistry; D012486:Salmonella typhimurium / Q000737:chemistry / Q000235:genetics
D001426:Bacterial Proteins; C071266:FlgM protein, Bacteria