Bentley A Fane
Professor, BIO5 Institute
Professor, Genetics - GIDP
Professor, Immunobiology
Professor, Plant Sciences
Professor, Applied BioSciences - GIDP
Primary Department
Department Affiliations
(520) 626-6634
Work Summary
Upon infection, viruses must transport their genomes into cells and produce progeny, often under a strict time deadline. We study how the viral proteins interact with with each other and with host cell proteins to efficiently accomplish these processes.
Research Interest
Bentley A. Fane, PhD, is a Professor in the School of Plant Sciences, College of Agriculture and Life Sciences and holds a joint appointment in the Department of Immunobiology, Arizona College of Medicine. Dr. Fane has an international reputation for his research into virus structure, assembly and evolution. His research focuses on the viruses of the Microviridae, of which he is considered one of the leading experts. He has been instrumental in defining the biochemical and structural parameters that allow these viruses to replicate and produce progeny in as little as five minutes. The rapid lifecycle has facilitated in depth studies into how viruses evolved resistance mechanism to anti-viral proteins targeting particle assembly.He has published over 60 original research paper in leading scientific journals, including Nature, Molecular Cell, and Journal of Virology, in which his publications on the evolution of resistance mechanisms and kinetic traps have been selected by the journal editors as articles of “significant interest.” He is a frequent presenter at national and international meetings, and has been invited to State of the Art and plenary talks at give the American Society for Virology. He presently serves on the Editorial Boards of two leading virology journals: Virology and the Journal of Virology. At the University of Arizona, Dr. Fane has been actively involved in promoting undergraduate research has been honored with teaching awards on the department, college, and university levels. Keywords: Virus structure and assembly, Viral DNA translocation, Viral evolution

Publications

Christakos, K. J., Chapman, J. A., Fane, B. A., & Campos, S. K. (2015). PhiXing-it, displaying foreign peptides on bacteriophage ΦX174. Virology, 488, 242-248.
BIO5 Collaborators
Samuel K Campos, Bentley A Fane

Although bacteriophage φX174 is easy to propagate and genetically tractable, it is use as a peptide display platform has not been explored. One region within the φX174 major spike protein G tolerated 13 of 16 assayed insertions, ranging from 10 to 75 amino acids. The recombinant proteins were functional and incorporated into infectious virions. In the folded protein, the peptides would be icosahedrally displayed within loops that extend from the protein׳s β-barrel core. The well-honed genetics of φX174 allowed permissive insertions to be quickly identified by the cellular phenotypes associated with cloned gene expression. The cloned genes were easily transferred from plasmids to phage genomes via recombination rescue. Direct ELISA validated several recombinant virions for epitope display. Some insertions conferred a temperature-sensitive (ts) protein folding defect, which was suppressed by global suppressors in protein G, located too far away from the insertion to directly alter peptide display.

Cherwa Jr., J. E., & Fane, B. A. (2009). Complete virion assembly with scaffolding proteins altered in the ability to perform a critical conformational switch. Journal of Virology, 83(15), 7391-7396.

PMID: 19474099;PMCID: PMC2708623;Abstract:

In the φX174 procapsid, 240 external scaffolding proteins form a nonquasiequivalent lattice. To achieve this arrangement, the four structurally unique subunits must undergo position-dependent conformational switches. One switch is mediated by glycine residue 61, which allows a 30° kink to form in α-helix 3 in two subunits, whereas the helix is straight in the other two subunits. No other amino acid should be able to produce a bend of this magnitude. Accordingly, all substitutions for G61 are nonviable but mutant proteins differ vis-à-vis recessive and dominant phenotypes. As previously reported, amino acid substitutions with side chains larger than valine confer dominant lethal phenotypes. Alone, these mutant proteins appear to have little or no biological activity but rather require the wild-type protein to interact with other structural proteins. Proteins with conservative substitutions for G61, serine and alanine, have now been characterized. Unlike the dominant lethal proteins, these proteins do not require wild-type subunits to interact with other viral proteins and cause assembly defects reminiscent of those conferred by the lethal dominant proteins in concert with wild-type subunits. Although atomic structures suggest that only a glycine residue can provide the proper torsion angle for assembly, mutants that can productively utilize the altered external scaffolding proteins were isolated, and the mutations were mapped to the coat and internal scaffolding proteins. Thus, the ability to isolate strains that could utilize the single mutant D protein species would not have been predicted from past structural analyses. Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Rossmann, M. G., Dokland, T., Bemal, R., McKenna, R., Dag, L. L., & Fane, B. A. (1998). Structure of a viral procapsid with molecular scaffolding. FASEB Journal, 12(8), A1332.

Abstract:

Scaffolding proteins often play a catalytic role in the assembly process, rather like molecular chaperones. Although macromolecular assembly processes are fundamental to all biological systems, they have been characterized most thoroughly in viral systems, such as the icosahedral Eschcrichia coli bacteriophage 4X174. The XI74 virion contains the proteins F, G, H and I. During assembly, two scaffolding proteins B and D are required for the formation of a 108S, 360-A diameter procapsid from pentameric precursors containing the F, G and H proteins. The procapsid contains 240 copies of protein D, forming an external scaffold, and 60 copies each of the internal scaffolding protein B, the capsid protein F, and the spike protein G. Maturadon involves packaging of DNA andJ proteins and loss of protein B, producing a 132S intermediate. Subsequent removal of the external scaffold yields the mature virion. Both the F and G proteins have the eight-stranded antiparallel -sandwich motif common to many plant and animal viruses. The structure of a procapsid-like particle at 3.5 A resolution will be described, showing how the scaffolding proteins coordinate assembly of the virus by interactions with the F and G proteins, and the F protein undergoes conformational changes during capsid maturation.

Cherwa, J. E., Tyson, J., Bedwell, G. J., Brooke, D., Edwards, A. G., Dokland, T., Prevelige, P. E., & Fane, B. A. (2017). ϕX174 Procapsid Assembly: Effects of an Inhibitory External Scaffolding Protein and Resistant Coat Proteins In Vitro. Journal of Virology (article was selected for the journal's "Spotlight" section), 91(1).

During ϕX174 morphogenesis, 240 copies of the external scaffolding protein D organize 12 pentameric assembly intermediates into procapsids, a reaction reconstituted in vitro In previous studies, ϕX174 strains resistant to exogenously expressed dominant lethal D genes were experimentally evolved. Resistance was achieved by the stepwise acquisition of coat protein mutations. Once resistance was established, a stimulatory D protein mutation that greatly increased strain fitness arose. In this study, in vitro biophysical and biochemical methods were utilized to elucidate the mechanistic details and evolutionary trade-offs created by the resistance mutations. The kinetics of procapsid formation was analyzed in vitro using wild-type, inhibitory, and experimentally evolved coat and scaffolding proteins. Our data suggest that viral fitness is correlated with in vitro assembly kinetics and demonstrate that in vivo experimental evolution can be analyzed within an in vitro biophysical context.

Fane, B., Villafane, R., Mitraki, A., & King, J. (1991). Identification of global suppressors for temperature-sensitive folding mutations of the P22 tailspike protein. Journal of Biological Chemistry, 266(18), 11640-11648.

PMID: 1828803;Abstract:

Suppressor mutations which alleviate the defects in folding mutants of the P22 gene 9 tailspike protein have recently been isolated (Fane, B. and King, J. (1991) Genetics 127, 263-277). The starting folding defects were in missense polypeptide chains generated by host amino acid insertions at different amber mutant sites. Fragments of genes carrying the amber mutations with and without their independently isolated suppressor mutations were cloned and sequenced. The parental nonsense mutations were located at Q45, K122, E156, W202, W207, Y232, and W365. Their conformational suppressors were single amino acid substitutions at a limited set of sites, V84>A, V331>A, and A334>V. The V331>A or A334>V suppressors were independently recovered starting with different mutant sites suggesting that they acted by some global or general mechanism. When the V331>A and A334>V mutations were crossed into well-characterized temperature-sensitive folding (tsf) mutants at various sites in the tailspike protein, they suppressed all of the eight tsf mutants tested. Since the tsf defects destabilize folding intermediates rather than the native conformation, this result implies that the suppressors act in the folding pathway. Strains carrying the isolated suppressor mutations displayed no obvious phenotypic defect and formed native biologically active tailspikes. Thus, these single amino acid substitutions have striking influences on the efficiency of intracellular chain folding, without causing functional defects in the native protein.