AMENDMENT
      NUMBER 1 TO TRUST AGREEMENT

    LEHMAN
      XS TRUST, SERIES 2007-15N

     

    This
      is
      Amendment Number 1, dated as of November 1, 2007 and effective as of December
      21, 2007 (this “Amendment”), to the Trust Agreement, dated as of July 1, 2007
      (the “Agreement”), by and among STRUCTURED ASSET SECURITIES CORPORATION., a
      Delaware corporation, as depositor (the “Depositor”), AURORA LOAN SERVICES LLC,
      as master servicer (the “Master Servicer”), and U.S. BANK NATIONAL ASSOCIATION,
      a national banking association, as trustee (the “Trustee”), relating to the
      Lehman XS Trust Mortgage Pass-Through Certificates, Series
      2007-15N.

     

    WHEREAS,
      Section 11.03 of the Agreement provides that under the circumstances and subject
      to the conditions set forth therein, the Agreement may be amended from time
      to
      time; 

     

    THEREFORE,
      in accordance therewith and in consideration of the mutual agreements herein
      contained, each party hereto agrees to amend the Agreement to the extent and
      on
      the terms set forth herein for the benefit of the other parties and of the
      Certificateholders.

     

    ARTICLE
      I

     

    DEFINITIONS

     

    SECTION
      1.01. Cross
      Reference to Definitions in Agreement.
      Capitalized terms used in this Amendment and not defined herein or amended
      by
      the terms of this Amendment shall have the meaning assigned to such terms in
      the
      Agreement.

     

    ARTICLE
      II

     

    EFFECTIVENESS

     

    SECTION
      2.01. Section 11.03 of the Agreement provides that the Agreement may be amended
      from time to time by the Depositor, the Master Servicer and the Trustee, with
      the consent of the NIMS Insurer, if any, but without the consent of the Swap
      Counterparty (except to the extent that the rights or obligations of (1) the
      Swap Counterparty thereunder or (2) the Swap Counterparty under the Swap
      Agreement (or the ability of the Trustee on behalf of the Supplemental Interest
      Trust to perform fully and timely its obligations under the Swap Agreement),
      are
      affected thereby, in which case prior written consent of the Swap Counterparty
      is required) and without notice to or the consent of any of the Holders to
      cause
      the provisions of the Agreement to conform to or be consistent with or in
      furtherance of the statements made with respect to the Offering Document.
      Section 11.03 of the Agreement further provides that no such amendment shall,
      as
      evidenced by an Opinion of Counsel, result in an Adverse REMIC Event and that
      prior to entering into any such amendment without the consent of Holders, the
      Trustee and the NIMS Insurer, if any, shall be provided with an Opinion of
      Counsel addressed to the Trustee and the NIMS Insurer, if any, (at the expense
      of the party requesting such amendment) to the effect that such amendment is
      permitted under such Section 11.03. 

     


    
      
        
        

      

      
        
        

        
          

        

      

      
        
        

      

    


    SECTION
      2.02. By their execution of this Amendment, the Depositor, the Master Servicer
      and the Trustee evidence their desire to make the amendments to the Agreement
      set forth below.

     

    ARTICLE
      III

     

    AMENDMENTS
      TO THE AGREEMENT

     

    SECTION
      3.01. Amendments.
      

     

    The
      definition of “Pool 4 Senior Priority” is hereby deleted and replaced in its
      entirety with the following:

     

    “Pool
      4
      Senior Priority:
      For the
      Pool 4 Senior Certificates, sequentially in the following order: (i) up to
      the
      amount of any Net Negative Amortization previously allocated to such
      Certificates and not repaid, to the Pool 4 Senior Certificates (other than
      the
      Exchangeable Certificates related to Pool 4) pro rata based on the amount of
      such unpaid prior allocations of Net Negative Amortization to each class thereof
      and (ii) pro rata (a) to the Class 4-A1 Underlying Interest, (b) sequentially,
      first, to the Class 4-A2A Underlying Interest and second, to the Class 4-A2B
      Underlying Interest, in that order, and (c) to the Class 4-A3 Underlying
      Interest.”

     

    ARTICLE
      IV

     

    MISCELLANEOUS

     

    SECTION
      4.01. Counterparts.
      This
      Amendment may be executed in two or more counterparts (and by different parties
      on separate counterparts), each of which shall be an original, but all of which
      together shall constitute one and the same instrument.

     

    SECTION
      4.02. Headings.
      The
      headings herein are for purposes of reference only and shall not otherwise
      affect the meaning or interpretation or any provision hereof.

     

    SECTION
      4.03. Agreement
      in Full Force and Effect as Amended.
      Except
      as specifically amended or waived hereby, all of the terms and conditions of
      the
      Agreement shall remain in full force and effect. All references to the Agreement
      in any other document or instrument shall be deemed to mean such Agreement
      as
      amended by this Amendment. This Amendment shall not constitute a novation of
      the
      Agreement, but shall constitute an amendment thereof. The parties hereto agree
      to be bound by the terms and obligations of the Agreement, as amended by this
      Amendment, as though the terms and obligations of the Agreement were set forth
      herein.

     

    SECTION
      4.04 Conditions
      to Effectiveness.
      This
      Amendment shall become effective upon the receipt by the Trustee of the opinion
      of counsel referred to in Section 11.03 of the Agreement.

     

    SECTION
      4.05. Governing
      Law.
      THIS
      AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF
      THE
      STATE OF NEW YORK, WITHOUT REFERENCE TO ITS CONFLICTS OF LAW
      PROVISIONS.

     


    
      
        
        

      

      
        2

        
          

        

      

      
        
        

      

    


    [SIGNATURE
      PAGE IMMEDIATELY FOLLOWS]

     


    
      
        
        

      

      
        3

        
          

        

      

      
        
        

      

    


    IN
      WITNESS WHEREOF, the Depositor, the Trustee and the Master Servicer have caused
      their names to be signed hereto by their respective officers hereunto duly
      authorized as of the day and year first above written.

     

    STRUCTURED
      ASSET SECURITIES CORPORATION, as Depositor

    


    


    By:      

    Name:
      Michael C. Hitzmann

    Title:
      Senior Vice President

    


    


    U.S.
      BANK
      NATIONAL ASSOCIATION, 

    not
      in
      its individual capacity, but solely 

    as
      Trustee

    


    


    By:      

    Name:
      

    Title:
      

    


    


    AURORA
      LOAN SERVICES LLC, 

    as
      Master
      Servicer

    


    


    By:      

    Name:
      Michele Olds

    Title:
      Vice President