This is a family of lipoproteins found only in pathogenic mycobacteria. These pathogenic lipoproteins may play a role in host-pathogen interactions. Lipoproteins localised to the cell-envelope of pathogenic bacteria are major determinants of virulence. The proteins are localised to the cell-surface via an N-terminal lipidation carried out by a transferase - pro-lipoprotein diacylglyceryl transferase Lgt - which attaches a diacylglyceride molecule to a sulfur atom from a crucial cysteine, and a consecutively acting lipoprotein signal peptidase LspA that cleaves the signal peptide just before the modified cysteine. When the peptidase is inactivated the pathogen has difficulty in replicating inside macrophages [1].

1: Crystal structure of Mycobacterium tuberculosis LppA, a lipoprotein confined to pathogenic mycobacteria. Grana M, Bellinzoni M, Bellalou J, Haouz A, Miras I, Buschiazzo A, Winter N, Alzari PM; Proteins. 2010;78:769-772. PMID:19899167