Alpha-helical domain is essential for antimicrobial activity of high mobility group nucleosomal binding domain 2 (HMGN2).
OBJECTIVE
To examine the antimicrobial spectrum and functional structure of high mobility group nucleosomal binding domain 2 (HMGN2).


METHODS
OMIGA protein structure software was used to analyze the two-dimensional structure of HMGN2. Synthetic short peptides were generated for studying the relationship between function and structure. Prokaryotic expression vectors were constructed for the holo-HMGN2 and its helical domain. Their E coli-based products were also prepared for antimicrobial testing. The antimicrobial assay included minimal effective concentration, minimal inhibitory concentration, and minimal bactericidal concentration.


RESULTS
OMIGA protein structure software analysis revealed a transmembrane alpha-helical structure (the putative antimicrobial domain) located from position 18 to 48 of the HMGN2 protein sequence. The antimicrobial assay showed that the MIC of the recombinant holo-HMGN2 against E coli ML-35p (an ampicillin-resistance strain), Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231 were 12.5, 25, and 100 mg/L, respectively. Against the same microorganisms, the MIC of the synthetic HMGN2 alpha-helical domain were 12.5, 25, and 100 mg/L, respectively, that is, the same as with the recombinant form of HMGN2. In contrast, recombinant holo-HMGN2 was inactive against Staphylococcus aureus ATCC 25923. The synthetic N-terminal and C-terminal fragments of HMGN2 had no antimicrobial activity against E coli ML-35p, P aeruginosa ATCC 27853 or C albicans ATCC 10231.


CONCLUSIONS
HMGN2 showed potent antimicrobial activity against E coli ML-35p, P aeruginosa ATCC 27853 and, to some extent, against C albicans ATCC 10231, but was inactive against S aureus ATCC 25923 in these assay systems. Itos alpha-helical structure may be essential for the antimicrobial activity of HMGN2.
Feng
Yun
Y
Research Unit of Infection and Immunity, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, China. fengyunxixi@yahoo.com.cn
Huang
Ning
N
Wu
Qi
Q
Bao
Lang
L
Wang
Bo-yao
BY
D000890:Anti-Infective Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D024242:HMGN2 Protein / Q000138:chemical synthesis / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D017434:Protein Structure, Tertiary / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000187:drug effects; D014170:Transformation, Genetic
D000890:Anti-Infective Agents; D024242:HMGN2 Protein