CAB-Align: A Flexible Protein Structure Alignment Method Based on the Residue-Residue Contact Area

Area of Science:

• Structural bioinformatics
• Computational biology
• Protein structure analysis

Background:

• Protein flexibility is crucial for function, but rigid-body alignment methods overlook this.
• Existing methods struggle to identify residue equivalences in flexible protein regions.

Purpose of the Study:

• Develop a new protein structure alignment method, CAB-align, to address limitations of rigid-body approaches.
• Identify homologous relationships at the residue level by considering physical contacts instead of 3D coordinates.

Main Methods:

• Developed CAB-align, a contact area-based alignment method.
• Employs initial rigid-body alignment followed by iterative dynamic programming for optimal alignment.
• Utilizes residue-residue contact area to detect similarity regions.

Main Results:

• CAB-align demonstrates robust performance, achieving high-quality alignments with excellent coverage and accuracy.
• Consistently generates reliable multiple alignments.
• Effectively discriminates between homologous and nonhomologous protein pairs, including multi-domain proteins.

Conclusions:

• CAB-align accurately captures evolutionary relationships by focusing on physical contacts, outperforming state-of-the-art methods.
• The method is valuable for identifying homologous proteins, especially those with significant flexibility.
• CAB-align software is available for academic use.