Biology subjects

Goto, N. K.

Publications and source records attributed to Goto, N. K..

6 recordsLinked to original sources

bioRxiv2025

Mapping Functional Dynamics Hotspots for Protein Engineering with NMR Peak Intensity Analysis

Structural dynamics play a crucial role in protein function, and tuning these dynamics through mutagenesis has emerged as a promising strategy for enhancing activity. However, identifying dynamics hotspots for protein engineering remains a labor-intensive challenge. Here, we demonstrate that NMR peak intensity analysis--a rapid, qualitative method with residue-level resolution--can identify functionally relevant dynamic regions with high precision. Using a family of red fluorescent proteins (RFPs) as a case study, we reveal that flexibility in specific regions of their structures correlates with function. Specifically, as quantum yield increases, the side of the {beta}-barrel closest to the chromophore phenolate moiety becomes more rigid, while the opposite side, closest to the acylimine group, gains flexibility. Notably, the phenolate face corresponds to a mutational hotspot frequently targeted in directed evolution campaigns aimed at enhancing brightness, underscoring its functional significance. B-factor analysis of non-cryogenic X-ray crystal structures further supports our findings. Our results establish NMR peak intensity analysis as a promising tool for mapping functional dynamics hotspots to guide protein engineering campaigns.

biophysics↗

bioRxiv2023

TReSR: A PCR-compatible DNA sequence design method for engineering proteins containing tandem repeats

Protein tandem repeats (TRs) are motifs comprised of near-identical contiguous sequence duplications. They are found in approximately 14% of all proteins and are implicated in diverse biological functions facilitating both structured and disordered protein-protein and protein-DNA interactions. These functionalities make protein TR domains an attractive component for the modular design of protein constructs. However, the repetitive nature of DNA sequences encoding TR motifs complicates their synthesis and mutagenesis by traditional molecular biology workflows commonly employed by protein engineers and synthetic biologists. To address this challenge, we developed a computational protocol to significantly reduce the complementarity of DNA sequences encoding TRs called TReSR (for Tandem Repeat DNA Sequence Redesign). The utility of TReSR was demonstrated by constructing a novel constitutive repressor synthesized by duplicating the LacI DNA binding domain into a single-chain TR construct by assembly PCR. Repressor function was evaluated by expression of a fluorescent reporter delivered on a single plasmid encoding a three-component genetic circuit. The successful application of TReSR to construct a novel TR-containing repressor with a DNA sequence that is amenable to PCR-based construction and manipulation will enable the incorporation of a wide range of TR-containing proteins for protein engineering and synthetic biology applications.

synthetic biology↗

bioRxiv2022

Computational remodeling of an enzyme conformational landscape for altered substrate selectivity

Structural plasticity of enzymes dictates their function. Yet, our ability to rationally remodel enzyme conformational landscapes to tailor catalytic properties remains limited. Here, we report a computational procedure for tuning conformational landscapes that is based on multistate design. Using this method, we redesigned the conformational landscape of a natural aminotransferase to preferentially stabilize a less populated but reactive conformation, and thereby increase catalytic efficiency with a non-native substrate to alter substrate selectivity. Steady-state kinetics of designed variants revealed selectivity switches of up to 1900-fold, and structural analyses by room-temperature X-ray crystallography and multitemperature nuclear magnetic resonance spectroscopy confirmed that conformational equilibria favoured the target conformation. Our computational approach opens the door to the fine-tuning of enzyme conformational landscapes to create designer biocatalysts with tailored functionality.

biophysics↗

bioRxiv2019

A transient amphipathic helix in the PCSK9 prodomain facilitates low-density lipoprotein binding

Proprotein convertase subtilisin/kexin type-9 (PCSK9) is a ligand of low-density lipoprotein receptor (LDLR) that promotes LDLR degradation in late endosomes/lysosomes. In human plasma, 30-40% of PCSK9 is bound to LDL particles; however, the physiological significance of this interaction remains unknown. LDL binding in vitro requires a disordered N-terminal region in PCSK9s prodomain. Here we report that peptides corresponding to a predicted amphipathic -helix in the prodomain N-terminus adopted helical structure in a membrane-mimetic environment; this effect was greatly enhanced by an R46L substitution representing an athero-protective PCSK9 loss-of-function mutation. A helix-disrupting proline substitution within the putative -helical motif in full-length PCSK9 lowered LDL binding affinity >5-fold. Modeling studies suggested the transient -helix aligns multiple polar residues to interact with positive-charged residues in the C-terminal domain. Gain-of-function PCSK9 mutations associated with familial hypercholesterolemia (FH) and clustered at the predicted interdomain interface (R469W, R496W, F515L) inhibited LDL binding, which was abolished for the R496W variant. These studies inform on allosteric conformational changes in PCSK9 required for high-affinity binding to LDL particles. Moreover, we report the initial identification of FH-associated mutations that diminish the ability of PCSK9 to bind LDL, supporting that LDL association in the circulation inhibits PCSK9 activity.

molecular biology↗

bioRxiv2019

Origin of Conformational Dynamics in a Globular Protein

Protein structures are dynamic, undergoing specific motions that can play a vital role in function. However, the link between primary sequence and conformational dynamics remains poorly understood. Here, we studied how conformational dynamics can arise in a globular protein by evaluating the impact of individual substitutions of core residues in DANCER-3, a streptococcal protein G domain {beta}1 (G{beta}1) variant that we previously designed to undergo a specific mode of conformational exchange that has never been observed in the wild-type protein. Using a combination of solution NMR experiments and molecular dynamics simulations, we demonstrate that only two mutations are necessary to create this conformational exchange, and that these mutations work synergistically, with one destabilizing the native G{beta}1 structure and the other allowing two new conformational states to be accessed on the energy landscape. Overall, our results show how conformational dynamics can appear in a stable globular fold, a critical step in the molecular evolution of new dynamics-linked functions.

biophysics↗

bioRxiv2017

Rational design of proteins that exchange on functional timescales

Proteins are intrinsically dynamic molecules that can exchange between multiple conformational states, enabling them to carry out complex molecular processes with extreme precision and efficiency. Attempts to design novel proteins with tailored functions have mostly failed to yield efficiencies matching those found in nature because standard methods do not allow for the design of exchange between necessary conformational states on a functionally-relevant timescale. Here, we develop a broadly-applicable computational method to engineer protein dynamics that we term meta-multistate design. We used this methodology to design spontaneous exchange between two novel conformations introduced into the global fold of Streptococcal protein G domain {beta}1. The designed proteins, named DANCERs, for Dynamic And Native Conformational ExchangeRs, are stably folded and exchange between predicted conformational states on the millisecond timescale. The successful introduction of defined dynamics on functional timescales opens the door to new applications requiring a protein to spontaneously access multiple conformational states.

biophysics↗