“…Concerning the diderm envelope, lipoproteins are abundant in all subcellular compartments, including the periplasmic leaflet of IM, OM, and the surface of OM, which puts the focus squarely on how this set of proteins reaches the outer leaflet of the OM upon exposure to environmental cues. Leptospira , like other spirochetes, possesses a sec-dependent protein translocation system named T2SS, which is not found in Borrelia and Treponema , and could also utilize it to secrete surface lipoproteins that are partially unfolded proteins. , Our proteomics analysis showed an increase in TolC family proteins (LIC_11941, LIC_12575, and LIC_12693), which create trans periplasmic channels in the type I secretion system. , In the type II secretion system of L. interrogans (PATH:lic03070), Gsp proteins are crucial in releasing toxins and cell wall-degrading enzymes. , The current study identified GspC, GspG, GspD, GspN, and GspE. In response to the physiological conditions of infection, upregulation of orthologs (YajC, SecG, SecF, SecA, SecD, and signal peptidase I) of the Sec-translocation system was observed on the outer membrane, with YajC and signal peptidase I being notably significant (PATH:lic03060).…”