An alternative terminal step of the general secretory pathway in Staphylococcus aureus

A. Craney, M.M. Dix, R. Adhikary, B.F. Cravatt, F.E. Romesberg, mBio (2015) 6:e01178-15.
pubpic2015ccraneyWeidentify the S. aureus operon ayrRABC and show that once released from repression by AyrR, the protein products AyrABC together confer resistance to the SPase inhibitor arylomycin M131 by providing an alternate and novel method of releasing translocated proteins, and we demonstrate that AyrABC functionally complements SPase by mediating the processing of the normally secreted proteins. Overall, the data demonstrate that ayrRABC encodes a secretion stress-inducible alternate terminal step of the general secretory pathway.


The inhibition of type I bacterial signal peptidase: Biological consequences and therapeutic potential

A. Craney, F.E. Romesberg, Bioorg. Med. Chem. Lett. (2015) 25:4761–4766.
pubpic2015xxWe review the information gained from the use of SPase inhibitors as probes of prokaryote biology. A thorough understanding of the consequences of SPase inhibition and the mechanisms of resistance that arise are essential to the success of SPase as an antibiotic target. In addition to the role of SPase in processing secreted proteins, the use of SPase inhibitors has elucidated a previously unknown function for SPase in regulating cleavage events of membrane proteins.


An expanded genetic alphabet

D.A. Malyshev, F.E. Romesberg, Angew. Chem. Int. Ed. (2015) 54:11930–11944.
pubpic2015malyshevNatural nucleic acids and the genetic information they encode are limited by the use of only four nucleotides that form two base pairs, (d)G-(d)C and d(A)-dT/U. In the past decade, three classes of unnatural base pairs have been developed to a high level of proof-of-concept. This review summarizes their development and the potentially revolutionary applications that they are now enabling.


Origins of Y. pestis sensitivity to the arylomycin antibiotics and the inhibition of type I signal peptidase

D.B. Steed, J. Liu, E. Wasbrough, L. Miller, S. Halasohoris, J. Miller, B. Somerville, J.R. Hershfield, F.E. Romesberg, Antimicrob. Agents Chemother. (2015) 59:3887-3898.
pubpic2015steedWe demonstrate that arylomycin activity is conserved against a broad range of Y. pestis strains and that this activity results from SPase inhibition. The origins of the sensitivity are traced to an increased dependence on SPase that results from high levels of protein secretion under physiological conditions.


A putative Cro-like repressor contributes to arylomycin resistance in Staphylococcus aureus

A. Craney, F.E. Romesberg, Antimicrob. Agents Chemother. (2015) 59:3066-3074.
pubpic201craneyWe characterized the susceptibility of a panel of S. aureus strains to two arylomycin derivatives and observed a wide range of susceptibilities. We found that resistant strains were sensitized by co-treatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. Transcriptional profiling using growth inhibitory concentrations of arylomycin revealed further insight into how this pathogen copes with secretion stress.


Adaptive mutations alter antibody structure and dynamics during affinity maturation

R. Adhikary, W. Yu, M. Oda, T. Chen, R. Walker, R. Stanfield, I. Wilson, J. Zimmermann, F.E. Romesberg, Biochemistry (2015) 54:2085–2093.
pubpic2015adhikaryIn this work, three affinity matured anti-MPTS antibodies (Abs) are characterized via X-ray and spectroscopic studies and the results are discussed in terms of the elasticity, anelasticity, and plasticity of the complexes. We find that the level of plasticity of the Ab-MPTS complexes is correlated with specificity, suggesting that the optimization of protein dynamics may have contributed to affinity maturation.


Axinellamines as broad-spectrum antibacterial agents: scalable synthesis and biology

R.A. Rodriguez, D.B. Steed, Y. Kawamata, S. Su, P.A. Smith, T.C. Steed, F.E. Romesberg, P.S. Baran, J. Am. Chem. Soc. (2014) 136:15403-15413.
pubpic2014rodriguezIn this collaborative work with the Baran Lab, we show that the axinellamines have promising activity against Gram-positive and Gram-negative bacteria, suggesting that their scaffold has the potential for further development. Details regarding their mode of action remain to be elucidated, but the axinellamines appear to cause secondary membrane destabilization and may inhibit normal septum formation..