Structural studies on Laz, a promiscuous anticancer Neisserial protein

Abstract

Azurin and Laz (lipidated azurin) are 2 bacterial proteins with anticancer, anti-viral and anti-parasitic activities. Azurin, isolated from the bacterium Pseudomonas aeruginosa, termed Paz, demonstrates anticancer activity against a range of cancers but not against brain tumors. In contrast, Laz is produced by members of Gonococci/Meningococci, including Neisseria meningitides which can cross the blood-brain barrier to infect brain meninges. It has been previously reported that Laz has an additional 39 amino acid moiety, called an H.8 epitope, in the N-terminal part of the azurin moiety that allows Laz to cross the entry barrier to brain tumors such as glioblastomas. Exactly, how the H.8 epitope helps the azurin moiety of Laz to cross the entry barriers to attack glioblastoma cells is unknown. In this paper, we describe the structural features of the H.8 moiety in Laz using X-ray crystallography and demonstrate that while the azurin moiety of Laz adopts a b-sandwich fold with 2 b-sheets arranged in the Greek key motif, the H.8 epitope was present as a disordered structure outside the Greek key motif. Structures of Paz and H.8 epitope-deficient Laz are well superimposed. The structural flexibility of the H.8 motif in Laz explains the extracellular location of Laz in Neisseria where it can bind the key components of brain tumor cells to disrupt their tight junctions and allow entry of Laz inside the tumors to exert cytotoxicity.

The solution structure of the soluble form of the lipid-modified azurin from Neisseria gonorrhoeae , the electron donor of cytochrome c peroxidase

“…As a remark, the structure reported here is similar to one determined for the Zn-Laz from the same organism using X-ray crystallography (PDB ID 3AY2) [17], with a backbone RMSD of 0.6 Å and an all atom RMSD of 1.2 Å.…”

“…In the case of azurin, the fifth copper ligand is an oxygen from the carbonyl peptide bond of a glycine that is coordinating the copper atom, making the geometry more bipyramidal [15]. The structure of N. gonorrhoeae Laz incorporating Zn instead of Cu was recently determined by X-ray at 1.9 Å resolution (PDB ID 3AY2) [17]. In this work, we proceeded to solve the solution structure with Cu so as to evaluate any differences between Zn-Laz and the native like form especially since Zn(II) prefers a quadrangular planar geometry.…”

Bacterial delivery of the anti-tumor azurin-like protein Laz to glioblastoma cells

“…The structural flexibility of the H.8 motif in Laz explains the extracellular location of Laz in Neisseria. Being surface exposed enables Laz to bind the key components of brain tumor cells to disrupt their tight junctions and allow entry of Laz inside the tumors to exert cytotoxicity (Hashimoto et al 2015). Both azurin and Laz possess anticancer activities.…”