3WJV

Crystal structure of the L68E variant of mLolB

Summary for 3WJV

• Entry DOI: 10.2210/pdb3wjv/pdb
• Related: 3wjt 3wju
• Descriptor: Outer-membrane lipoprotein LolB, SULFATE ION (3 entities in total)
• Functional Keywords: lola/lolb fold, outer membrane, transport protein
• Biological source: Escherichia coli
• Cellular location: Cell outer membrane; Lipid-anchor (By similarity): C9QXY7
• Total number of polymer chains: 1
• Total formula weight: 21433.80

Authors

Takeda, K.,Tokuda, H.,Miki, K. (deposition date: 2013-10-16, release date: 2014-03-05, Last modification date: 2023-11-08)

Primary citation

Hayashi, Y.,Tsurumizu, R.,Tsukahara, J.,Takeda, K.,Narita, S.,Mori, M.,Miki, K.,Tokuda, H.
Roles of the Protruding Loop of Factor B Essential for the Localization of Lipoproteins (LolB) in the Anchoring of Bacterial Triacylated Proteins to the Outer Membran
J.Biol.Chem., 289:10530-10539, 2014

PubMed Abstract: The Lol system comprising five Lol proteins, LolA through LolE, sorts Escherichia coli lipoproteins to outer membranes. The LolCDE complex, an ATP binding cassette transporter in inner membranes, releases outer membrane-specific lipoproteins in an ATP-dependent manner, causing formation of the LolA-lipoprotein complex in the periplasm. LolA transports lipoproteins through the periplasm to LolB on outer membranes. LolB is itself a lipoprotein anchored to outer membranes, although the membrane anchor is functionally dispensable. LolB then localizes lipoproteins to outer membranes through largely unknown mechanisms. The crystal structure of LolB is similar to that of LolA, and it possesses a hydrophobic cavity that accommodates acyl chains of lipoproteins. To elucidate the molecular function of LolB, a periplasmic version of LolB, mLolB, was mutagenized at various conserved residues. Despite the lack of acyl chains, most defective mutants were insoluble. However, a derivative with glutamate in place of leucine 68 was soluble and unable to localize lipoproteins to outer membranes. This leucine is present in a loop protruding from mLolB into an aqueous environment, and no analogous loop is present in LolA. Thus, leucine 68 was replaced with other residues. Replacement by acidic, but not hydrophobic, residues generated for the first time mLolB derivatives that can accept but cannot localize lipoproteins to outer membranes. Moreover, deletion of the leucine with neighboring residues impaired the lipoprotein receptor activity. Based on these observations, the roles of the protruding loop of LolB in the last step of lipoprotein sorting are discussed.

PubMed: 24569999
DOI: 10.1074/jbc.M113.539270

Experimental method

X-RAY DIFFRACTION (2.4 Å)