Structural studies on Laz, a promiscuous anticancer Neisserial protein.

Area of Science:

• Biochemistry
• Structural Biology
• Oncology

Background:

• Azurin and lipidated azurin (Laz) are bacterial proteins with therapeutic potential.
• Laz, unlike azurin (Paz), can target brain tumors due to its H.8 epitope.
• The mechanism by which the H.8 epitope facilitates brain tumor entry is unclear.

Purpose of the Study:

• To elucidate the structural features of the H.8 epitope in Laz.
• To understand how the H.8 epitope enables Laz to cross the blood-brain barrier and target glioblastomas.

Main Methods:

• X-ray crystallography was used to determine the structure of the H.8 moiety in Laz.
• Structural comparison of Laz, Paz, and H.8 epitope-deficient Laz.

Main Results:

• The azurin moiety of Laz exhibits a conserved β-sandwich fold.
• The H.8 epitope was found to be a disordered structure.
• The H.8 motif's structural flexibility allows extracellular binding to brain tumor cells, disrupting tight junctions and enabling tumor entry.

Conclusions:

• The disordered and flexible structure of the H.8 epitope is key to Laz's ability to target brain tumors.
• This flexibility facilitates disruption of brain tumor cell junctions, allowing Laz to enter and exert cytotoxicity.
• Laz represents a promising therapeutic agent for glioblastomas.