Many species of pathogenic gram‐positive bacteria display covalently crosslinked protein polymers (called pili or fimbriae) that mediate microbial adhesion to host tissues. These structures are assembled by pilus‐specific sortase enzymes that join the pilin components together via lysine‐isopeptide bonds. The archetypal SpaA pilus from Corynebacterium diphtheriae is built by the CdSrtA pilus‐specific sortase, which crosslinks lysine residues within the SpaA and SpaB pilins to build the shaft and base of the pilus, respectively. Here, we show that CdSrtA crosslinks SpaB to SpaA via a K139(SpaB)‐T494(SpaA) lysine‐isopeptide bond. Despite sharing only limited sequence homology, an NMR structure of SpaB reveals striking similarities with the N‐terminal domain of SpaA (NSpaA) that is also crosslinked by CdSrtA. In particular, both pilins contain similarly positioned reactive lysine residues and adjacent disordered AB loops that are predicted to be involved in the recently proposed “latch” mechanism of isopeptide bond formation. Competition experiments using an inactive SpaB variant and additional NMR studies suggest that SpaB terminates SpaA polymerization by outcompeting NSpaA for access to a shared thioester enzyme–substrate reaction intermediate.

Academic departments, research clusters and evaluators analyze author and citation data to measure research impact and to support strategic planning. We created a tool, Scholar Metrics Scraper (SMS), to automate the retrieval of this bibliometric data for our research team. The project contains Jupyter notebooks (publicly-shared here) that take a list of researchers as an input to export a CSV file of citation metrics from Google Scholar and figures to visualize the group's impact. SMS is a scalable, open and publicly-accessible solution for automating the retrieval of citation data over time for a group of researchers.