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SecB-like translocase or SecB export protein??

| posted 21 May, 2021 17:43
There is no appropriate official function for Gordonia phage Floral_39. There are, however, lots of hits for a SecB-like export protein or translocase. "The Escherichia coli soluble protein SecB is involved in the export of periplasmic and outer membrane proteins." Kumamoto CA. SecB protein: a cytosolic export factor that associates with nascent exported proteins. J Bioenerg Biomembr. 1990 Jun;22(3):337-51. doi: 10.1007/BF00763171. PMID: 2202722. Thoughts about this function?

Beckie Bortz
| posted 03 Jun, 2021 14:17
This protein certainly looks like a relative of SecB, whose actual function is as a chaperone in protein secretion that delivers its unfolded substrates to SecA. Looking quickly at the paper on the structure of SecB from Haemophilus influenzae, I note that the phage protein doesn't conserve all the residues known to be important for the SecB-SecA interaction, so I don't think it's likely that it does what SecB does. Whether it could be a chaperone at all is a good question, and a more difficult one. If anything, I might consider calling it a SecB-related protein, but I'm not too comfortable going beyond that.
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