Vibrio vulnificus metalloprotease VvpE has no direct effect on the iron-assimilation from human holotransferrin.
In order to elucidate the role of Vibrio vulnificus metalloprotease VvpE in the uptake of iron from human transferrin, we constructed a VvpE-deficient mutant and a merozygotic vvpE-transcriptional reporter from the wild type strain MO6-24/O. All three strains were able to grow only in deferrated Heart Infusion broth (DF-HI) with human holotransferrin (HT), but not in DF-HI containing partially iron-saturated transferrin or apotransferrin, without noticeable differences among the strains. All strains consumed most iron in the early growth phase. Both the transcription and extracellular production of VvpE proceeded at undetectable levels when bacterial growth was severely retarded in the DF-HI. When HT or FeCl(3) was added to the DF-HI, the retarded bacterial growth was restored and vvpE transcription dramatically increased in the late growth phase, but the extracellular VvpE production was negligible as compared to its transcription. All strains were unable to degrade HT even in normal HI broth containing HT, in which extracellular VvpE activity was remarkably high. The uptake of iron from HT in all strains was consistent with the production of catechol-siderophore rather than hydroxamate-siderophore. Similar results were also observed when clinical isolates from septicemic patients were used. In conclusion, we determined that VvpE was not directly involved in the siderophore-mediated iron-uptake from human transferrin. In addition, the discrepancy between the transcription and extracellular production of VvpE suggests that additional posttranscriptional events are involved in the extracellular production of VvpE.
Shin
Sung-Heui
SH
Research Center for Resistant Cells and Department of Microbiology, Chosun University Medical School, 375 Seosuk-Dong, Dong-Gu, Gwangju 501-759, Republic of Korea. shsin@chosun.ac.kr
Sun
Hui-Yu
HY
Park
Ra-Young
RY
Kim
Choon-Mee
CM
Kim
Soo-Young
SY
Rhee
Joon-Haeng
JH
D003470:Culture Media / Q000737:chemistry; D015870:Gene Expression; D050939:Gene Fusion; D017930:Genes, Reporter; D006801:Humans; D007501:Iron / Q000378:metabolism*; D045726:Metalloproteases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D017262:Siderophores / Q000032:analysis; D014158:Transcription, Genetic; D014168:Transferrin / Q000378:metabolism*; D041261:Vibrio vulnificus / Q000201:enzymology* / Q000254:growth & development; D001616:beta-Galactosidase / Q000032:analysis
D003470:Culture Media; D017262:Siderophores; D014168:Transferrin; C110714:holotransferrin; D007501:Iron; D001616:beta-Galactosidase; D045726:Metalloproteases