MyMpn Project

About ~ Mycoplasma Pneumoniae

Mycoplasma pneumoniae, a bacterium of the Mollicutes class (Latin: soft skin), is characterized by a minimal cell size, the lack of a cell wall, and a minimal genome with low GC content. Mycoplasmas have evolved through extensive genome reduction from a bacillus (Clostridium-like) ancestor of the Firmicutes taxon, resulting in a limitation of their metabolic capabilities and thus in a parasitic modus vivendi (they have never been found as freely living organisms). Their natural habitats include hosts from all over the plant and animal kingdoms. M. pneumoniae is a human pathogen that colonizes the respiratory epithelium, causing a primary atypical pneumonia, that cannot be treated with classic beta-lactam antibiotics, due to the lack of peptidoglycan in this species. Moreover, M. pneumoniae and some of its relatives, are able to glide thanks to a specialized structure, the attachment organelle, which is thought to be involved in the infection process. The M. pneumoniae genome with a length of ~800 kbp has a coding capacity few more than 700 proteins. Although in nature this bacterium is found attached to the host cell surface or intracellularly, it can be grown anexically, provided that its demanding nutrient requirements are met. M. pneumoniae is one of the smallest organisms yet described that can be grown in vitro and, despite its simplicity, it resembles more complex bacteria in several ways. For example, its energy metabolism is very close to that of Lactococci, and like other pathogenic bacteria it uses antigenic variation to escape the host immune system. Moreover, it has a sophisticated intracellular organization based on a cytoskeleton, which probably involves indifferent processes like motility and cell division. Therefore, M. pneumoniae is small enough to be studied exhaustively and at the same time complex enough to address general issues, making it an exceptional model for Systems Biology, especially for understanding an organism in its entirety.

Mycoplasma pneumoniae genetic code

Mycoplasma pneumoniae do not use the standard genetic code, but the same as mitochondria, the opal stop codon being utilized for tryptophan.

TTT Phenylalanine (Phe, F)	TCT Serine (Ser, S)	TAT Tyrosine (Tyr, Y)	TGT Cysteine (Cys, C)
TTC Phenylalanine (Phe, F)	TCC Serine (Ser, S)	TAC Tyrosine (Tyr, Y)	TGC Cysteine (Cys, C)
TTA Leucine (Leu, L) i	TCA Serine (Ser, S)	TAA * Ter	TGA Tryptophan (Trp, W)
TTG Leucine (Leu, L) i	TCG Serine (Ser, S)	TAG * Ter	TGG Tryptophan (Trp, W)
CTT Leucine (Leu, L)	CCT Proline (Pro, P)	CAT Histidine (His, H)	CGT Arginine (Arg, R)
CTC Leucine (Leu, L)	CCC Proline (Pro, P)	CAC Histidine (His, H)	CGC Arginine (Arg, R)
CTA Leucine (Leu, L)	CCA Proline (Pro, P)	CAA Glutamine (Gln, Q)	CGA Arginine (Arg, R)
CTG Leucine (Leu, L) i	CCG Proline (Pro, P)	CAG Glutamine (Gln, Q)	CGG Arginine (Arg, R)
ATT Isoleucine (Ile, I) i	ACT Threonine (Thr, T)	AAT Asparagine (Asn, N)	AGT Serine (Ser, S)
ATC Isoleucine (Ile, I) i	ACC Threonine (Thr, T)	AAC Asparagine (Asn, N)	AGC Serine (Ser, S)
ATA Isoleucine (Ile, I) i	ACA Threonine (Thr, T)	AAA Lysine (Lys, K)	AGA Arginine (Arg, R)
ATG Methionine (Met, M) i	ACG Threonine (Thr, T)	AAG Lysine (Lys, K)	AGG Arginine (Arg, R)
GTT Valine (Val, V)	GCT Alanine (Ala, A)	GAT Aspartic acid (Asp, D)	GGT Glycine (Gly, G)
GTC Valine (Val, V)	GCC Alanine (Ala, A)	GAC Aspartic acid (Asp, D)	GGC Glycine (Gly, G)
GTA Valine (Val, V)	GCA Alanine (Ala, A)	GAA Glutamic acid (Glu, E)	GGA Glycine (Gly, G)
GTG Valine (Val, V) i	GCG Alanine (Ala, A)	GAG Glutamic acid (Glu, E)	GGG Glycine (Gly, G)

Mycoplasma pneumoniae phylogenic tree

This phylogenic tree has been created using the iTOL software (http://itol.embl.de). It shows the Mycoplasmae species inside the Bacteriae, and position them related to B.subtilis and E.coli.