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EXHIBIT 5.1
[WILSON SONSINI GOODRICH & ROSATI LETTERHEAD]
October 4, 2000
Kosan Biosciences Incorporated
3832 Bay Center Place
Hayward, California 94545
RE: REGISTRATION STATEMENT ON FORM S-1
Ladies and Gentlemen:
We have examined the Registration Statement on Form S-1 filed by you with
the Securities and Exchange Commission on March 31, 2000 (Registration No.
333-33732) (the "Registration Statement"), in connection with the registration
under the Securities Act of 1933, as amended, of up to 5,750,000 shares of your
Common Stock, par value $0.001 per share (the "Shares"). The Shares include an
over-allotment option granted to the underwriters of the offering to purchase
750,000 shares. We understand that the Shares are to be sold to the underwriters
of the offering for resale to the public as described in the Registration
Statement. As your legal counsel, we have examined the proceedings taken, and
are familiar with the proceedings proposed to be taken, by you in connection
with the sale and issuance of the Shares.
It is our opinion that the Shares have been duly authorized and that, upon
completion of the proceedings being taken or contemplated by us, as your
counsel, to be taken prior to the issuance of the Shares, including the
proceedings being taken in order to permit such transaction to be carried out in
accordance with applicable state securities laws, the Shares, when issued and
sold in the manner described in the Registration Statement and in accordance
with the resolutions adopted by the Board of Directors of the Company, will be
legally and validly issued, fully paid and nonassessable.
We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever appearing in the
Registration Statement, including the prospectus constituting a part thereof,
and any amendments thereto.
Very truly yours,
/s/ WILSON SONSINI GOODRICH & ROSATI
Professional Corporation
