Small envelope protein E of SARS: cloning, expression, purification, CD determination, and bioinformatics analysis.
OBJECTIVE
To obtain the pure sample of SARS small envelope E protein (SARS E protein), study its properties and analyze its possible functions.


METHODS
The plasmid of SARS E protein was constructed by the polymerase chain reaction (PCR), and the protein was expressed in the E coli strain. The secondary structure feature of the protein was determined by circular dichroism (CD) technique. The possible functions of this protein were annotated by bioinformatics methods, and its possible three-dimensional model was constructed by molecular modeling.


RESULTS
The pure sample of SARS E protein was obtained. The secondary structure feature derived from CD determination is similar to that from the secondary structure prediction. Bioinformatics analysis indicated that the key residues of SARS E protein were much conserved compared to the E proteins of other coronaviruses. In particular, the primary amino acid sequence of SARS E protein is much more similar to that of murine hepatitis virus (MHV) and other mammal coronaviruses. The transmembrane (TM) segment of the SARS E protein is relatively more conserved in the whole protein than other regions.


CONCLUSIONS
The success of expressing the SARS E protein is a good starting point for investigating the structure and functions of this protein and SARS coronavirus itself as well. The SARS E protein may fold in water solution in a similar way as it in membrane-water mixed environment. It is possible that beta-sheet I of the SARS E protein interacts with the membrane surface via hydrogen bonding, this beta-sheet may uncoil to a random structure in water solution.
Shen
Xu
X
Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China.
Xue
Jian-Hua
JH
Yu
Chang-Ying
CY
Luo
Hai-Bin
HB
Qin
Lei
L
Yu
Xiao-Jing
XJ
Chen
Jing
J
Chen
Li-Li
LL
Xiong
Bin
B
Yue
Li-Duo
LD
Cai
Jian-Hua
JH
Shen
Jian-Hua
JH
Luo
Xiao-Min
XM
Chen
Kai-Xian
KX
Shi
Tie-Liu
TL
Li
Yi-Xue
YX
Hu
Geng-Xi
GX
Jiang
Hua-Liang
HL
D002942:Circular Dichroism; D019295:Computational Biology; D028941:Coronavirus 229E, Human / Q000737:chemistry; D017938:Coronavirus, Bovine / Q000737:chemistry; D017939:Coronavirus, Canine / Q000737:chemistry; D006801:Humans; D008958:Models, Molecular; D006517:Murine hepatitis virus / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000302:isolation & purification; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D045169:Severe Acute Respiratory Syndrome / Q000821:virology*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification
D014759:Viral Envelope Proteins