is ecoli suseptable if only a steptomycin coding gene is introduced?

Answer 1

Streptomycin is an antibiotic. It kills bacteria, including E.coli, by interfering with translation through its interaction with the 30S ribosomal subunit protein RpsL.

E.coli will not be susceptible to it, if they have a mutation in the rspL gene or if you introduce a gene that codes for a protein which gives resistance to streptomycin.

If you mean that you are cloning the gene of an enzyme that is involved in the synthesis of streptomycin, then you hould know that there is a whole pathway for this synthesis. This means that there several reactions and thus several enzymes required.
Cloning only one of them is certainly not enough to produce the antibiotic and kill the bacteria. In fact for some of them there won't be even an appropriate substrate to act upon in the E.coli (because of the absence of enzymes that are more upstream in the pathway that would produce the substrate).
However you could have different effects on cell viability depending on the exact nature of the enzyme and the degree of its expression.

Answer 2

E. coli SHOULD be sensitive to streptomycin, that is, the antibiotic should normally kill E. coli. The cells could be made resistant by introducing a streptomycin resistance gene into the cells.