protein transportation

Zhengyu Sha zsha at
Tue Jan 12 16:31:26 EST 1993

In <1iuvuiINNf0k at> Mark A. Saper <saper at> write:

>I know about the periplasmic transport proteins ... these all have leader
>sequences.  Is the protein that you are working with known to not have a
>leader sequence?

I have cloned and seqed a catalase gene which I purified the enzyme from periplasmic fraction from B.abortus which is a gram-negative bacterium. N-terminal amino acid sequence of the purified enzyme show no cleavable leader sequence. The a.a. sequence predicted by the nuceotide seq. also did not show any signal-like sequences. I checked the a.a. sequence of the periplasmic catalase of E.coli HP I(Biochem.Biophys.Res.Comm. 154:392-397) in the gene bank and could not find a leader sequence too. A recent mini

review in J.B. said membrane and periplasmic bacterial proteins used the uniformal secretion mechanism. In  contrast, some of the extracellular proteins use self-promoted extracellular secretion mechanisms. I wonder if anyone has any idea? 

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