Biology subjects

Anderson, W. F.

Publications and source records attributed to Anderson, W. F..

3 recordsLinked to original sources

bioRxiv2022

Structure of the Monkeypox profilin-like protein A42R reveals potential function differences from cellular profilins

The infectious disease human monkeypox is spreading rapidly in 2022 causing a global health crisis. The genomics of the monkeypox virus (MPXV) have been extensively analyzed and reported, although little is known about the virus-encoded proteome. In particular, there is almost no structure information about MPXV proteins, other than computational models. Here we report a 1.52 [A] x-ray structure of the MPXV protein A42R, the only MPXV-encoded protein with a known structure. This protein shows sequence similarity to profilins, which are cellular proteins known to function in regulation of actin cytoskeletal assembly. However, structural comparison of the A42R with known members of the profilin family reveals critical differences that support prior biochemical findings that this protein only weakly binds actin and does not bind poly(L-proline). In addition, the analysis suggests that this protein may have distinct interactions with phosphatidylinositol lipids. Overall, our data suggest that the role of A42R in replication of orthopoxviruses may not be easily determined by comparison to cellular profilins. Further, our findings support a need for increased efforts to determine high-resolution structures of other MPXV proteins to inform physiological studies of the poxvirus infection cycle and to reveal potential new strategies to combat human monkeypox should the infection become more common in the future.

microbiology↗

bioRxiv2018

The spermidine acetyltransferase SpeG regulates transcription of the small RNA RprA

Spermidine N-acetyltransferase (SpeG) acetylates and thus neutralizes toxic polyamines. Studies indicate that SpeG plays an important role in virulence and pathogenicity of many bacteria, which have evolved SpeG-dependent strategies to control polyamine concentrations and survive in their hosts. In Escherichia coli, the two-component response regulator RcsB is reported to be subject to N{varepsilon}-acetylation on several lysine residues, resulting in reduced DNA binding affinity and reduced transcription of the small RNA rprA; however, the physiological acetylation mechanism responsible for this behavior has not been fully determined. Here, we performed an acetyltransferase screen and found that SpeG inhibits rprA promoter activity in an acetylation-independent manner. Surface plasmon resonance analysis revealed that SpeG can physically interact with the DNA-binding carboxyl domain of RcsB. We hypothesize that SpeG interacts with the DNA-binding domain of RcsB and that this interaction might be responsible for SpeG-dependent inhibition of RcsB-dependent rprA transcription. This work provides a model for SpeG as a modulator of E. coli transcription through its ability to interact with the transcription factor RcsB. This is the first study to provide evidence that an enzyme involved in polyamine metabolism can influence the function of the global regulator RcsB, which integrates information concerning envelope stresses and central metabolic status to regulate diverse behaviors.

microbiology↗

bioRxiv2018

Listeria monocytogenes InlP interacts with afadin and facilitates basement membrane crossing

During pregnancy, the placenta protects the fetus against the maternal immune response, as well as bacterial and viral pathogens. Bacterial pathogens that have evolved specific mechanisms of breaching this barrier, such as Listeria monocytogenes, present a unique opportunity for learning how the placenta carries out its protective function. We previously identified the L. monocytogenes protein Internalin P (InlP) as a secreted virulence factor critical for placental infection (1). Here, we show that InlP, but not the highly similar L. monocytogenes internalin Lmo2027, binds to human afadin (encoded by AF-6), a protein associated with cell-cell junctions. A crystal structure of InlP reveals several unique features, including an extended leucine-rich repeat (LRR) domain with a distinctive Ca2+-binding site. Despite afadins involvement in the formation of cell-cell junctions, MDCK epithelial cells expressing InlP displayed a decrease in the magnitude of the traction stresses they could exert on deformable substrates, similar to the decrease in traction exhibited by AF-6 knock-out MDCK cells. L. monocytogenes {Delta}inlP mutants were deficient in their ability to form actin-rich protrusions from the basal face of polarized epithelial monolayers, a necessary step in the crossing of such monolayers (transcytosis). A similar phenotype was observed for bacteria expressing an internal in-frame deletion in inlP (inlP DLRR5) that specifically disrupts its interaction with afadin. However, afadin deletion in the host cells did not rescue the transcytosis defect. We conclude that secreted InlP targets cytosolic afadin to specifically promote L. monocytogenes transcytosis across the basal face of epithelial monolayers, which may contribute to the crossing of the basement membrane during placental infection.

microbiology↗