Library approaches to biophysical problems.
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Biophysical Phenomena↗
Biomedical subjects
Lynne Regan
Publications and source records attributed to Lynne Regan.
Covariation of backbone motion throughout a small protein domain.
The synchronization (correlation) of conformational fluctuations in folded proteins may influence the rates of enzyme catalysis and ligand binding as well as the stabilities of native proteins and their complexes. However, experimental detection of correlated motions remains difficult. Herein, we present an analysis of the covariation of NMR-derived backbone dynamical parameters among a family of ten mutants of a small protein. Both the spatial restriction and the time scales of backbone motions exhibit a higher degree of covariation than would be expected if the internal motions of each group were independent, providing experimental support for correlated dynamics. Application of this approach to other proteins may reveal dynamical correlations that influence catalysis, ligand-binding and/or protein stability.
Mutation↗
Molten globules move into action.
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Antibodies↗
TPR proteins: the versatile helix.
Tetratrico peptide repeat (TPR) proteins have several interesting properties, including their folding characteristics, modular architecture and range of binding specificities. In the past five years, many 3D structures of TPR domains have been solved, revealing at a molecular level the versatility of this basic fold. Here, we discuss the structure of TPRs and highlight the diversity of arrangements and functions that are associated with these ubiquitous domains. Genomic analyses of the distribution of TPR domains are presented along with implications for protein engineering.
Amino Acid Sequence↗
The folding and design of repeat proteins: reaching a consensus.
Although they are widely distributed across kingdoms and are involved in a myriad of essential processes, until recently, repeat proteins have received little attention in comparison to globular proteins. As the name indicates, repeat proteins contain strings of tandem repeats of a basic structural element. In this respect, their construction is quite different from that of globular proteins, in which sequentially distant elements coalesce to form the protein. The different families of repeat proteins use their diverse scaffolds to present highly specific binding surfaces through which protein-protein interactions are mediated. Recent studies seek to understand the stability, folding and design of this important class of proteins.
Amino Acid Motifs↗
Design of stable alpha-helical arrays from an idealized TPR motif.
The tetratricopeptide repeat (TPR) is a 34-amino acid alpha-helical motif that occurs in over 300 different proteins. In the different proteins, three to sixteen or more TPR motifs occur in tandem arrays and function to mediate protein-protein interactions. The binding specificity of each TPR protein is different, although the underlying structural motif is the same. Here we describe a statistical approach to the design of an idealized TPR motif. We present the high-resolution X-ray crystal structures (to 1.55 and 1.6 A) of designed TPR proteins and describe their solution properties and stability. A detailed analysis of these structures provides an understanding of the TPR motif, how it is repeated to give helical arrays with different superhelical twists, and how a very stable framework may be constructed for future functional designs.
Amino Acid Motifs↗
Mutations in the B1 domain of protein G that delay the onset of amyloid fibril formation in vitro.
We previously reported that under certain experimental conditions, many variants of the B1 domain of IgG-binding protein G from Streptococcus form fibrils reproducibly. The variant I6T53 was the focus of the present study because the lag phase in the kinetics of fibril formation by this variant is significantly longer than that of other variants. This lag phase is distinguished by changes in both intrinsic fluorescence intensity and in light scattering of the protein. NMR diffusion measurements suggest that the soluble protein during the lag phase is monomeric. The kinetic profiles of fibril formation are found to depend on experimental conditions. The first kinetic phase diminishes almost completely when the reaction is seeded with preformed amyloid fibrils.
Amyloid↗
Does the location of a mutation determine the ability to form amyloid fibrils?
We have previously reported studies of fibril formation by a set of protein G B1 domain (beta1) variants, with mutations located around the central parallel beta-strands. In this study, we designed multiple mutations in the edge strands of beta1 to create proteins with a stability range comparable to that of the set of central mutants. All the edge variants are able to form amyloid fibrils when they are incubated at their melting temperatures. This result suggests that overall protein stability is the key determinant for amyloid formation and not the specific location of destabilizing mutations. The edge strand and variants cross-seed with each other and with members of the central variant family. Interesting fibrillar morphology was observed in some cross-seeding cases and its implications for a better understanding of nucleation and elongation events are discussed.
Amyloid↗