Braun’s lipoprotein Lpp (major outer membrane lipoprotein, murein lipoprotein) is the most abundant protein in E. coli, and it is also the only known protein which is covalently connected to the peptidoglycan layer. However, a detailed understanding of its distribution on the peptidoglycan layer is not clear yet.

In the research paper published in Science Advances on January 20^th, researchers from Shandong University, Ocean University of China, University of Sheffield and University of Liverpool used atomic force microscopy to investigate the localization of Lpp on E. coli peptidoglycan sacculi.

They found that Lpp can be visualized on peptidoglycan layer using atomic force microscopy. The results revealed that Lpp proteins are homogeneously distributed over the outer surface of the sacculus at a high density. However, it is absent from septum during cell division, when the peptidoglycan associated lipoprotein Pal is present, revealing an unexpected mutual exclusive interaction between the two proteins. The research established a framework to elucidate the distribution of Lpp, and other peptidoglycan bound proteins.

Sheng Qi, Zhang Mengyao, Liu Simin from Shandong University are the co-first authors of this paper. Su Hainan, Zhang Yuzhong from Shandong University, and Simon Foster from University of Sheffield are the corresponding authors.

Link to the paper: https://www.science.org/doi/10.1126/sciadv.add8659