Compositions and methods for improving expression and / or 
secretion of 
protein or polypeptide of interest in a host 
cell are provided. Compositions comprising a coding sequence for a bacterial 
secretion signal peptide are provided. The coding sequences can be used in vector constructs or expression systems for transformation and expression of a 
protein or polypeptide of interest in a host 
cell. The compositions of the invention are useful for increasing accumulation of properly processed proteins in the 
periplasmic space of a host 
cell, or for increasing 
secretion of properly processed proteins from the host cell. In particular, isolated secretion 
signal peptide-encoding 
nucleic acid molecules are provided. Additionally, 
amino acid sequences corresponding to the 
nucleic acid molecules are encompassed. In particular, the present invention provides for isolated 
nucleic acid molecules comprising 
nucleotide sequences encoding the 
amino acid sequences shown in SEQ ID NO: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24, and the 
nucleotide sequences set forth in SEQ ID NO: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23, as well as variants and fragments thereof.