Recombinant Haemophilus influenzae UPF0208 membrane protein NTHI1376 (NTHI1376)

Introduction to Haemophilus influenzae and NTHI1376

Haemophilus influenzae is a bacterium known to cause a variety of infectious diseases, particularly in children, such as meningitis, pneumonia, and otitis media . Nontypeable Haemophilus influenzae (NTHi) strains, which lack a polysaccharide capsule, are a primary cause of bacterially induced acute exacerbations of chronic obstructive pulmonary disease (COPD) . NTHi adheres to and invades host respiratory epithelial cells, allowing it to persist in the lower airways of adults with COPD .

NTHI1376 refers to a specific protein within Haemophilus influenzae. Further details about its function, structure, and role are not available in the provided context.

NTHI1441 as a Virulence Factor

NTHI1441, another protein in Haemophilus influenzae, has been identified as a virulence factor contributing to the bacterium's ability to invade human respiratory epithelial cells . An isogenic knockout mutant of the open reading frame NTHI1441 showed a significant reduction (76.6% ± 5.5%) in the invasion of human bronchial and alveolar epithelial cells . The decreased invasion occurred independently of intracellular survival or adherence to cells .

2.1. Conservation and Expression

The NTHI1441 gene is conserved among NTHi genomes and does not change during persistence in the airways of individuals with COPD . The NTHI1441 protein expresses extracellular epitopes on the bacterial cell surface and is a target of serum antibodies following infection in adults with COPD, suggesting its expression during infection of the human respiratory tract .

2.2. Potential Therapeutic Target

Due to its role in host cell invasion, conservation among strains, and expression of surface-exposed epitopes, NTHI1441 is considered a potential target for preventative and therapeutic interventions for diseases caused by NTHi .

Protein Structure Overview

Proteins are composed of amino acids linked by peptide bonds, and their structure can be described at four levels .

Protein Structure Prediction

Protein structure prediction involves inferring the three-dimensional structure of a protein from its amino acid sequence . The conformational flexibility around the torsion angles φ and ψ at the Cα atom allows for many possible arrangements of the polypeptide chain . Interactions such as hydrogen bonding between the main chain NH and CO groups contribute to the formation of secondary structures like α helices and β sheets .