# Presentation: 657327

## Update on Joint ASCAC-BERAC Panel on Modeling for GTL

- Rick Stevens
- John Wooley

## Participants

**Panel Members:**
- Michael Banda  LBNL
- Thomas Zacharia  ORNL
- David Galas  ISB/Battelle
- Rick Stevens  ANL/UChicago
- *John Wooley  UCSD
- *David Kingsbury  Moore Foundation
- *Keith Hodgson  Stanford
- *Barbara Wold  Caltech
- *Chris Somerville  Stanford

**Invited Presenters:**
- Nitin Baliga  ISB/U Washington
- Rich Bonneau  NYU/Courant
- Paramvir Dehal  LBNL/UCB
- Justin Donato  U Wisconsin
- Thierry Emonet  Yale University
- Adam Feist  UCSD
- Mick Follows  MIT
- Peter Karp  SRI
- Harley McAdams  Stanford
- Sue Rhee  Carnegie Institution
- Nagiza Samatova  ORNL

- * BERAC members

## The Subcommittee Charge

- Convene a joint panel with BERAC to examine the issue of computational models for GTL, including:
- How progress could be accelerated through targeted investments in applied mathematics, and computer science and how these can be incorporated to meet the needs of computational biology.
- The joint panel should consider whether the current ASCR long-term goal is too ambitious, given the status and level of buy-in from the community.
- 	“By 2015, demonstrated progress toward developing through the Genomes to Life partnership with the Biological and Environmental Research program, the computational science capability to model a complete microbe and simple microbial community.”
- It needs to consider what is happening in the computational-science and life-sciences communities. It should discuss possible intermediate goals that might be more relevant to the two programs.
- And it should identify the key computational obstacles to developing computer models of the major biological understandings necessary to characterize and engineer microbes for DOE missions, such as biofuels and bioremediation.

## Status of the “Modeling in GTL” Report

- Preliminary findings and recommendations
- These are being revised by the joint panel over the next few weeks
- Preparing background material for the report from the panel presentations
- 10-15 page summary to provide context for the findings and recommendations
- Generating linkages to two important NRC reports that impact the modeling charge
- The role of theory in advancing 21st Century Biology (Galas et. al.)
- Catalyzing Inquiry at the Interface of Computing and Biology (Wooley, Lin et. al.)

## Computational Modeling and Simulation asEnablers for Biological Discovery

- Some Ways Models are Useful in Biology
- Models Provide a Coherent Framework for Interpreting Data
- Models Highlight Basic Concepts of Wide Applicability
- Models Uncover New Phenomena or Concepts to Explore
- Models Identify Key Factors or Components of a System
- Models Can Link Levels of Detail (Individual to Population)
- Models Enable the Formalization of Intuitive Understandings
- Models Can Be Used as a Tool for Helping to Screen Unpromising Hypotheses
- Models Inform Experimental Design
- Models Can Predict Variables Inaccessible to Measurement
- Models Can Link What Is Known to What Is Yet Unknown
- Models Can Be Used to Generate Accurate Quantitative Predictions
- Models Expand the Range of Questions That Can Meaningfully Be Asked

- From the NRC report “Catalyzing Inquiry at the Interface of Computing and Biology”

## Data-driven Predictive Model Building

## Response to 60Co- rays: a static model

- Whitehead et al. Nature MSB (2006)

**P19**

**  ****Descriptive**
**Static**
**Dynamic**
**  ****Quantitative**
**  ****Mechanistic**

## From molecules to population behavior

- Stochastic molecular events
- “Modules”: group of molecules that carry out a cellular function
- Network of modules in single cells
- Single cell behavior
- Communication between cells
- Population behavior

- Physiological scales

- Intracellular

- Cellular

- Population

## Bacterial chemotaxis sensory system

- Information processing unit
- Chemotaxis network

- Bren & Eisenbach, 2000

## Slide 13

## EGRIN models relationships among diverse cellular processes

- Baliga Lab, submitted

## What is the relationship between the structure of a pathway and its function?

**What is the relationship between the structure of a pathway and its function?**

- Unlike EMP pathway in anaerobic bacteria,   *Z. mobilis* utilizes **ED** pathway like aerobes
- Two genes (incl. *mdh*) are **missing** in *Z. mobilis* TCA cycle  **low biomass**.
- All genes except for 6-P-fructokinase are present in EMP pathway  **inactive EMP**.

- Higher sugar uptake & ethanol yield
- Lower biomass production
- Higher ethanol tolerance
- Facultative anaerobic bacteria

**Pyruvate**

_**Example Findings:**_

**Why *****Z. mobilis*****?**

_**Hypothesis**_**: The ****topology**** of a pathway alters organismal phenotypic functions and is evolutionarily conserved across phenotypically similar genomes.**

## Carbon Cycle 

- Efficiency of biological nutrient export regulates atmospheric CO2

## “Natural Selection” approach: 

***“******Natural Selection” approach:***** **
** **initialize many potentially viable types
-  allow system to self-organize ...
-  fittest physiologies (parameter combinations) succeed
-  less fit physiologies “excluded”

- P

- P

- Complex initialized food web            self-organized state

##  Plausible analogs of Prochlorococcus ecotypes present in solutions

- Biogeography

-  Plausible analogs of *Prochlorococcus *ecotypes present in solutions
-  *Prochlorococcus* analogs defined by:
-  high surface area:vol
-  inability to utilize nitrate
-  appropriate light, T sensitivities selected

- model-ecotypes

*Prochlorococcus* ecotypes
- AMT13 (Johnson et al., 2006)‏

**Finding.** _Modeling and simulation is beginning to play a critical role in integrating our understanding of biological mechanisms at multiple levels, including specific cellular subsystems such as metabolism, motility, signaling, regulation, differentiation and development._
- These are critical areas of understanding that are relevant to advancing DOE mission areas.
- The community is ready to take big steps in the direction of more complete models, models that incorporate more detailed biological mechanisms and to apply these models to more areas of biological science.
- We note that integrative modeling of biological systems complements the relatively well developed field of atomistic modeling (e.g. molecular dynamics, etc.) which can contribute to DOE mission areas in biology, but which is not sufficient to meet the long-term bioengineering goals alone.

## Finding.  While there has been considerable progress in advancing integrative modeling during the last decade (as witnessed in the high quality of presentations heard by the subcommittee) this progress has been largely driven by a relatively small number of research groups that have been successful at piecing together research support from a number of disparate sources (e.g. NIH, NSF, DOE, DAPRA). 

- There is not currently a long-term research program of appropriate scale aimed explicitly at developing biological modeling and simulation capabilities relevant to DOE missions.

## Finding.  The ASCR supported components of the GTL program are not currently supporting projects in applied mathematics or computer science primarily targeted at developing integrated modeling and simulation capabilities for microbes or plants. 

## Recommendation 1. The ten year OMB PART goal for ASCR the joint modeling and simulation activity of ASCR and BER be modified to read

*“**(ASCR) By 2018, demonstrate significant advances in the capability to predict an organisms’ phenotype from its genome sequence, through advances in genome sequence annotation, whole genome scale modeling and simulation and integrated model driven experimentation”*
- This PART goal should be accompanied by a specific set of metrics of progress, example metrics could include for a given organism: *the fraction of an organism’s genes and gene products included in a model, number of correct metabolic phenotype measurements predicted, number of transcription regulatory elements in a model, number of correct gene expression experiments predicted, fraction of correct predictions of essential genes, number of organisms for which predictive models can be generated, etc.*

## Recommendation 2.  DOE should develop an explicit research program aimed at achieving significant progress on the overarching goal of predictive modeling and simulation in DOE relevant biological systems. 

- This program should be a joint effort between ASCR and BER and should include a diversity of modeling approaches.
- The program should leverage existing experimental activities as well as support the development of new experimental activities that are directly tied to the needs of developing predictive models.
- This new research program should be aimed at advancing the state-of-the-art of cell modeling directly, should include equal participation from biologists and mathematicians, computer scientists and engineers and should be indirectly coupled to the more applied goals of bioenergy, carbon cycle research or bioremediation.
- This program will need to be supported at a large-enough scale that a multiple target approach can be pursued that will enable progress on many intermediate goals simultaneously by different research groups.

## Recommendation 3.  DOE should establish an annual conference that focuses on highlighting the progress in predictive modeling in biological systems.  

- This meeting should be an open meeting and separate from any programmatic PI meeting.
- One goal of the meeting would be to establish a series of scientific “indicators” of progress in predictive modeling, similar to successful indicators associated with the competitive assessment of structure prediction (CASP).
- These types of measures will enable the community to benchmark progress on methods and will be critical to assessing the impact of the research program on fundamentally advancing the state-of-the-art.
- Example metrics could include predicting essentiality in microbial genomes, predicting gene expression patterns in novel environments, to predicting yields in metabolic engineering scenarios.

## Finding.  Integrative modeling and simulation efforts are highly dependent on the curation of genomics data and associated integrated pathway and protein databases that support metabolic reconstruction, interpretation of microarrays and other experimental data.  

- These databases are the foundation for the development of models and provide the critical biological context for a given organism or problem.
- Through resources like NIH’s NCBI and NIAID and the dozens of community lead database projects there is reasonable coverage of model organisms (e.g. *Escherichia coli, Saccharomyces cerevisiae* and* Caenorhabditis elegans*, etc.) and pathogens, however there is not the same level of support for curating the data associated with organisms related to energy and the environment.

## Finding.  Modeling and simulation in microbial systems has advanced in many areas simultaneously.  

- Today for some systems we have useful and interesting predictive models for core metabolism, for global transcription regulation, for signaling and motility control and for life-cycle development and differentiation.
- _However we do not yet have many integrated models that include two or more of these capabilities._
- Also the successful examples in each case are typically limited to a few model systems and have not be generally extended to the hundreds of organisms relevant to DOE whose genomes are now available.

## Recommendation 4. The modeling and simulation research program should be supported by an explicit series of investments in the modeling technology, database and algorithms and infrastructure needed to address the computational challenges. 

**Recommendation 4.** _The modeling and simulation research program should be supported by an explicit series of investments in the modeling technology, database and algorithms and infrastructure needed to address the computational challenges. _
- The appropriate early targets for a comprehensive attack on predictive biological modeling are specific functions of microbial organisms (e.g. cellular metabolism, motility, global transcription regulation and differentiation and life-cycle development).
- The focus should include advancing the predictive skill on well studied models (e.g. *E. coli, B. subtilis*, etc.) but begin to push on to those organisms that stretch the capability beyond the existing well studied model systems (e.g. *Clostridium, Shewanella, Synechocystis*) and small consortia (communities) of microorganisms relevant to DOE missions such as those associated with bioremdiation, carbon sequestration and nitrogen fixation and fermentation and degradation.
- We also recommend that the lower eukaryotes (e.g. Diatoms, Coccolithopores, single cell fungi) and plants should be included as targets in longer-term modeling and simulation goals.

## Finding. There are a number of obstacles to reaching the visionary goal of a predictive model useful for engineering of an organism derived largely from its genome and related data, here we describe four of the relevant ones.

- First, we lack _integrated genomics databases_ and the associated computational methods for supporting curation, extension and visualization of comparative data explicitly focused on supporting the development of modeling and simulations for DOE relevant organisms.
- Second, we lack _robust mathematical frameworks_ and software implementing those frameworks for _integrating models of metabolism with those of gene regulation_ which are two of most highly developed areas of modeling and simulation at the whole cell level, but whose mathematical representations are quite different.
- Third, we lack the _multiscale mathematics and associated software libraries and tools for integrating processes in cellular models of disparate scales_ (e.g. molecular scale to that of the whole cell and microbial community) that would enable the modeling community to begin the process of integrated whole cell scale models with atomistic simulations of specific mechanisms.
- Fourth, all of computational biology should be framed in a _computational and analytical theory that incorporates evolution as the basis for understanding_ and interpreting the results from comparative analysis.  For example we have not yet developed the algorithms needed to make rapid progress on questions such as understanding the major forces governing the evolution of metabolism and regulatory networks.  Understanding these forces will be critical to creating the stable engineered strains needed for large scale bioproduction of materials.

## Recommendation 5.  DOE should establish a mechanism to support the long-term curation and integration of genomics and related datasets (annotations, metabolic reconstructions, expression data, whole genome screens, phenotype data, etc.) to support biological research in general and the needs of modeling and simulation in particular in areas of energy and the environment that are not well supported by NSF and NIH.   

- This mechanism should target the creation of a state-of-the-art community resource for data of all forms that are relevant to organisms of interest to DOE.
- This should be a joint activity of ASCR and BER with ASCR responsible for the database and computational infrastructure to enable community annotation and data sharing.  It should also leverage the work of established groups.

## Recommendation 6. DOE should work with the community to identify novel scientific opportunities for connecting modeling and simulation at the pathway and organism level to modeling and simulation at other space and temporal scales.  

- Examples that could be investigated include integration of microbial models into ocean and terrestrial ecology models which in turn are coupled to global climate models, and models of bioremediation environments that can couple organism metabolic capabilities to external biogeochemistry.
- This multiscale coupling is beginning to be explored, but much more can be done and it is likely to yield significant scientific insight.