Contribution of bovine lactoferrin inter-lobe region to iron binding stability and antimicrobial activity against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> |
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Authors: | Xuejing Bai Da Teng Zigang Tian Yanping Zhu Yalin Yang Jianhua Wang |
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Institution: | (1) Key Laboratory of Feed Biotechnology, Ministry of Agriculture, 100081 Beijing, People’s Republic of China;(2) Gene Engineering Laboratory, Feed Research Institute, Chinese Academy of Agricultural Sciences, 12 Zhongguancun Nandajie St., Haidian District, 100081 Beijing, People’s Republic of China; |
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Abstract: | The investigation of the recombinant bovine lactoferrin-derived antimicrobial protein (rBLfA) demonstrates that the inter-lobe
region of bovine lactoferrin contributes to iron binding stability and antimicrobial activity against Staphylococcus aureus. rBLfA containing N-lobe (amino acid residues 1–333) and inter-lobe region (residues 334–344) was expressed in Pichia pastoris at shaking flask and fermentor level. The recombinant intact bovine lactoferrin (rBLf) and N-lobe (rBLfN) were expressed
in the same system as control. The physical–chemical parameters of rBLfA, rBLfN and rBLf including amino acid residues, molecular
weight, isoelectric point, net positive charge and instability index were computed and compared. The simulated tertiary structure
and the calculated surface net charge showed that rBLfA maintained original structure and exhibited a higher cationic feature
than rBLf and rBLfN. The three proteins showed different iron binding stability and antimicrobial activity. rBLfA released
iron in the pH range of 7.0–3.5, whereas rBLfN lost its iron over the pH range of 7.0–4.0 and iron release from rBLf occurred
in the pH range of 5.5–3.0. However, the minimum inhibition concentration of rBLfA against S. aureus ATCC25923 was 6.5 μmol/L, compared with 12.5 and 25 μmol/L that of rBLfN and rBLf, respectively. These results revealed that
S. aureus was more sensitive to rBLfA than rBLfN and rBLf. It appeared that the strong cationic character of inter-lobe region related
positively to the higher anti-S. aureus activity. |
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