Search

Synchrotron protein crystallography (PX) remains an indispensable tool for uncovering the atomic structures of biomolecules. TLS 15A1, operated by the protein diffraction group of NSRRC, has been accessible to both academic and industrial users since January 2013. This beamline is energy‐tunable within a range between 5.6 and 15.5 keV, which is suitable for phasing experiments. Over the past 11 years, TLS 15A1 has supported 657 projects and facilitated 1523 experiments across 41,656 h of beamtime. This article describes the beamline layout, studies of factors influencing data quality, and significant scientific contributions. [ABSTRACT FROM AUTHOR]

Peptidoglycan (PG) sacculi surround the cytoplasmic membrane, maintaining cell integrity by withstanding internal turgor pressure. During cell growth, PG endopeptidases cleave the crosslinks of the fully closed sacculi, allowing for the incorporation of new glycan strands and expansion of the peptidoglycan mesh. Outer-membrane-anchored NlpI associates with hydrolases and synthases near PG synthesis complexes, facilitating spatially close PG hydrolysis. Here, we present the structure of adaptor NlpI in complex with the endopeptidase MepS, revealing atomic details of how NlpI recruits multiple MepS molecules and subsequently influences PG expansion. NlpI binding elicits a disorder-to-order transition in the intrinsically disordered N-terminal of MepS, concomitantly promoting the dimerization of monomeric MepS. This results in the alignment of two asymmetric MepS dimers respectively located on the two opposite sides of the dimerization interface of NlpI, thus enhancing MepS activity in PG hydrolysis. Notably, the protein level of MepS is primarily modulated by the tail-specific protease Prc, which is known to interact with NlpI. The structure of the Prc-NlpI-MepS complex demonstrates that NlpI brings together MepS and Prc, leading to the efficient MepS degradation by Prc. Collectively, our results provide structural insights into the NlpI-enabled avidity effect of cellular endopeptidases and NlpI-directed MepS degradation by Prc. The outer-membrane-anchored protein NlpI recruits multiple MepS endopeptidases to enhance peptidoglycan breakdown. It also connects MepS to the protease Prc for efficient degradation, providing insights into how NlpI regulates cell wall remodeling. [ABSTRACT FROM AUTHOR]