FlgM proteins from different bacteria exhibit different structural characteristics

Abstract

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.

Interaction of a Partially Disordered Antisigma Factor with Its Partner, the Signaling Domain of the TonB-Dependent Transporter HasR

“…The number of examples of partially disordered proteins involved in various biological processes is increasing. Among them, a partially disordered antisigma factor has been reported [49] . The antisigma factor FlgM binds to and inhibits the activity of σ28 directing the transcription of proteins involved in the bacterial flagellum formation.…”

The Role of Semidisorder in Temperature Adaptation of Bacterial FlgM Proteins

“…On the other hand, the corresponding thermophilic protein from Aquifex aeolicus has more secondary structure content (29) and the structure of its functional complex (PDB ID 1RP3) was determined by x-ray crystallography at 2.3 Å resolution (30). Further experimental studies of more FlgM proteins adapted at different temperatures revealed varying degrees of compactness and secondary structural content (31).…”

Disorder prediction-based construct optimization improves activity and catalytic efficiency of Bacillus naganoensis pullulanase

“…DisMeta analyzes a protein sequence using eight disorder prediction algorithms (DISEMBL, DISOPRED2, DISpro, FoldIndex, GlobPlot2, IUPred, RONN and VSL2). From each algorithm, disorder predictions are provided separately by the server, along with a plot showing the disorder levels of all amino acid residues in a protein sequence predicted by the algorithms 15 . In addition, protein sequence are also analyzed by seven sequence analysis tools (coils, ANCHOR, SignalP, TMHMM, SEG, PROFphd and PSIPred) to provide the information including secondary structure, binding site and complexity prediction 16 .…”