Philip Youderian . HYPERLINK mailto:email@example.com
Department of Microbiology, Molecular Biology, and Biochemistry.University
of Idaho.Moscow, Idaho 83844.(208) 885-0571 (office).(208) 885-7161 (lab).(208)
2. Recent publications:..Magrini, Vincent , Daniel Salmi, David Thomas,
Stephen K. Herbert, Patricia L. Hartzell, and Philip Youderian. 1997. Temperate
Myxococcus xanthus phage Mx8 encodes a DNA adenine methylase, Mox. J. Bacteriol.
179:.4254-4263...Salmi, Daniel, Vincent Magrini, Patricia L. Hartzell and
Philip Youderian. 1998. Genetic determinants of immunity and integration
of temperate Myxococcus xanthus phage Mx8. J. Bacteriol. 180: 614-621.
Salmi, Daniel, Chad Creighton, Michael L. Storms and Philip Youderian. 1998.
Temperate Myxococcus xanthus phage Mx8 integrase catalyzes the reversible,
covalent modification of its own coding sequence to regulate its specific
activity. J. Bacteriol. submitted.
Weimer, Robby M., Chad Creighton, Angela Stassinopoulos, Philip Youderian,
and Patricia Hartzell. 1998. A chaperone in the HSP70 family controls the
production of extracellular fibrils in Myxococcus xanthus. J. Bacteriol,
submitted...Creighton, Chad, Vincent Magrini, David White, Patricia L. Hartzell,
and Philip Youderian. 1998. The aadA gene of plasmid R100 confers resistance
to spectinomycin and streptomycin in Myxococcus xanthus. J. Bacteriol,.submitted.
Youderian, Philip. 1998. Bacterial motility: secretory secrets of gliding
bacteria. Curr. Biol., in press.
Youderian, Philip, Matthew C. Lawes, Chad Creighton, Jessica C. Cook and
Milton H. Saier, Jr. 1998. Mutations that confer resistance to 2-deoxyglucose
reduce the specific activity of hexokinase from Myxococcus xanthus. Mol.
Microbiol, submitted...3. Research interests:.
Mx8: The sequence of the Mx8 genome is now about 70% complete, and closure
should occur within the year. We are completing studies on its mechanism
of superinfection immunity, which appears to be regulated by a heterodimeric
repressor in the b-ZIP family of DNA-binding proteins.
Hexose catabolism: We have identified a hexokinase in M. xanthus, and have
initiated the detailed study of its kinetics, as well as those of E. coli
glucokinase. Both enzymes are inhibited by glucosamine and N-acetylglucosamine,
and we are investigating whether these hexoses may be alternate substrates.
In addition, we have found that whereas the M. xanthus enzyme is inhibited
by 2-deoxyglucose, the E. coli enzyme is stimulated by this hexose analogue,
and we are exploring its allosteric regulation, oligomerization state, etc.
Currently, we are in the process of purifying the M. xanthus enzyme to homogeneity
from 40 liters of wild-type cells, so that we can clone its structural gene
using reverse genetics, and overproduce and purify large amounts of the
protein for detailed mechanistic studies.
Gluconeogenic anabolism: .We have cloned the M. xanthus genes for glutamine
fructose-6-phosphate transamidase (gfaA and gfaB), the enzyme that catalyzes
the first committed step in hexosamine biosynthesis, and are studying their
differential regulation in response to development. This enzyme controls
the flow of carbon into the major hexosamine building blocks of the spore-coat
polysaccharides. Like R. meliloti, M. xanthus appears to make both vegetative
and development-specific forms of this key enzyme. In collaboration with
Bernard Badet, we are also exploring why this enzyme is the only glutamine-dependent
transamidase that cannot use ammonia as an amido-donor.
Smaller puzzles: (Ion transport) Using the PCR, we have fortuitously cloned
the helA gene from M. xanthus, and a portion of the arsenite antiporter/ATPase
operon. We are exploring how these transport systems are important for the
physiology of M. xanthus, which as a soil microorganism, must exclude these
nasty chemicals it encounters in soil microenvironments.
(Secreted nuclease) As part of my continuing work with Trish on the sglK
story, we are characterizing a gene nanA upstream of the two genes encoding
histone-like repressors of fibril production, which, in turn, lie immediately
upstream of the grpS-sglK operon. We would like to know what role the secreted
nuclease it encodes plays in the M. xanthus pathway of nucleotide salvage.
The Myxococcus xanthus genome: In collaboration with Ron Gill, we have taken
the cosmid library of M. xanthus, moved it into my beloved Salmonella typhimurium
using phage P1, and have shown that we can cross cosmid inserts onto phage
P22. We are in the process of developing a high-throughput strategy for
the mutagenesis and sequencing of cosmid inserts, starting with two 35 kb
P22 subclones of the dsp and rfb (O-antigen) loci, in collaboration with
John Downard and Heidi Kaplan, and our sequencing support group led by Greg
Buck and Greg Meyers at Commonwealth Biotechnologies, Inc. We expect to
complete the ordered, overlap cosmid map of M. xanthus by mid-September.
Also, we will have about 300 pools of mutant cosmids carrying selectable
insertions in every M. xanthus gene that can be crossed onto the M. xanthus
genome for functional analysis available for general use by October. We
have obtained approval from the NIH to submit a $1.5 million proposal to
complete the M. xanthus genome sequence, and with NIH support, we project
a 3-year time-scale for completion. Sequence and mutant data will be posted
monthly on the Myxo web site, starting in October, as we progress in our
4. Lab news:..a. Vince is looking for a post-doctoral position starting
in June of 1999, and wants to stay in the Myxo field. He has produced 4
publications in the past four years, and is likely to have several more
before he leaves..
b. Matthew Lawes has just joined our lab as a postdoctoral fellow. He comes
with the training to use the awesome power of Salmonella and P22 genetics
to sequence the M. xanthus genome.
.c. I am giving three talks at the Chilean Society for Microbiology meeting
in July, and spreading the good news about Myxo in Santiago, where I look
forward to spending a sabbatical in two years (after sequencing the Myxo
genome, por supuesto.) .