Neville, N. | bioRxiv Science

bioRxiv2023

Ionic polyphosphorylation of histidine repeat proteins by inorganic polyphosphate

Inorganic polyphosphate (polyP) is a linear polymer of orthophosphate that is present in nearly all organisms studied to date. A remarkable function of polyP involves its attachment to lysine residues via non-enzymatic post-translational modification (PTM) that is presumed to be covalent. Here, we show that proteins containing tracts of consecutive histidine residues exhibit a similar modification by polyP, which confers an electrophoretic mobility shift on NuPAGE gels. Our screen uncovered 30 human and yeast histidine repeat proteins that are specifically modified by polyP. This polyP modification is histidine-dependent and non-covalent in nature, though remarkably, it withstands harsh denaturing conditions--a hallmark of covalent PTMs. We have termed this interaction ionic histidine polyphosphorylation (iH-PPn) to describe its unique PTM-like properties. Importantly, we show that iH-PPn disrupts phase separation and phosphorylation activity of the human protein kinase DYRK1A, and inhibits the activity of the transcription factor MafB, highlighting iH-PPn as a potential hitherto unrecognized regulatory mechanism. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/536149v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@1ed34b7org.highwire.dtl.DTLVardef@200259org.highwire.dtl.DTLVardef@17a2954org.highwire.dtl.DTLVardef@12f5d04_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHICAL ABSTRACTC_FLOATNO C_FIG

biochemistry↗

bioRxiv2018

Structure-guided disruption of pseudopilus tip inhibits Type II secretion in Pseudomonas aeruginosa

Pseudomonas aeruginosa utilizes the Type II secretion system (T2SS) to translocate a wide range of large, structured protein virulence factors through the periplasm to the extracellular environment for infection. In the T2SS, five pseudopilins assemble into the pseudopilus that acts as a piston to extrude exoproteins out of cells. Through structure determination of the pseudopilin complexes of XcpVWX and XcpVW and function analysis, we have confirmed that two minor pseudopilins, XcpV and XcpW, constitute a core complex indispensable to the pseudopilus tip. The absence of either XcpV or -W resulted in the non-functional T2SS. Our small-angle X-ray scattering experiment for the first time revealed the architecture of the entire pseudopilus tip and established the working model. Based on the interaction interface of complexes, we have developed inhibitory peptides. The structure-based peptides not only disrupted of the XcpVW core complex and the entire pseudopilus tip in vitro but also inhibited the T2SS in vivo. More importantly, these peptides effectively reduced the virulence of P. aeruginosa towards Caenorhabditis elegans.

microbiology↗